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Digitized by the Internet Archive 
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TLhc tRural Science Series 

Edited et L. H. BAILEY 



THE POTATO 



Ejje l&ural Science JSmrg 

Edited by L. H. Bailey 

The Soil. King. , 

The Spraying of Plants. Lodeman. 

Milk and its Products. Wing. Enlarged and Bevised. 

The Fertility of the Land. Boberts. 

The Principles of Fruit-growing. Bailey. 20th 

Edition, Bevised. 
Bush-fruits. Card. Bevised. 
Fertilizers. Voorhees. Bevised. 
The Principles of Agriculture. Bailey. Bevised. 
Irrigation and Drainage. King. 
The Farmstead. Boberts. 
Eural Wealth and Welfare. Fairchild. 
The Principles of Vegetable-gardening. Bailey. 
Farm Poultry. Watson. Enlarged and Bevised. 
The Feeding of Animals. Jordan. (Now Rural 

Text-Book. ) 
The Farmer's Business Handbook. Boberts. 
The Diseases of Animals. Mayo. 
The Horse. Boberts. 
How to Choose a Farm. Hunt. 
Forage Crops. Voorhees. 

Bacteria in Relation to Country Life. Lipman. 
The Nursery-book. Bailey. 
Plant-breeding. Bailey and Gilbert. Bevised. 
The Forcing-book. Bailey. 

The Pruning-book. Bailey. (Now Rural Manual Series.) 
Fruit-growing in Arid Regions. Baddock and Whipple. 
Rural Hygiene. Ogden. 
Dry-farming. Widtsoe. 
Law for the American Farmer. Green. 
Farm Boys and Girls. McKeever. 
The Training and Breaking of Horses. Harper. 
Sheep-farming in North America. Craig. 
Cooperation in Agriculture. Powell. 
The Farm Woodlot. Cheyney and Wentling. 
Household Insects. Herrick. 
Citrus Fruits. Coit. 

Principles of Rural Credits. Morman. 
Beekeeping. Phillips. 

Subtropical Vegetable-gardening. Bolfs. 
Turf for Golf Courses. Piper and Oakley. 
The Potato. Gilbert. 



THE POTATO 



BY 



ARTHUR W. (JILBERT, Ph.D. 

PROFESSOR OF PLANT-BREEDING, NEW YORK STATE COLLEGE 
OF AGRICULTURE AT CORNELL UNIVERSITY 



ASSISTED BY 

MOBTIEB E. BABBITS, Ph.D. 

PROFESSOR OF PLANT PATHOLOGY, NEW YORK STATE COLLEGE 
OF AGRICULTURE AT CORNELL UNIVERSITY 

AND 

DANIEL DEAN 

FORMERLY PRESIDENT OF THE NEW YORK STATE 
POTATO ASSOCIATION 



THE MACMILLAN COMPANY 
1917 

All rights reserved 



5"3 



2^ 



Copyright, 1917, 
By THE MACMILLAN COMPANY. 

Set up and electrotyped. Published March, 191 7. 



MAR 29 1917 



J. S. Cushing Co. — Berwick & Smith Co. 
Norwood, Mass., U.S.A. 



©CI.A460074 



': • ( 



\ * ' 



PREFACE 

This book is intended to give brief and practical 
suggestions on the growing, breeding and marketing 
of potatoes. It is written especially for the practical 
farmer and the student who may wish concise informa- 
tion on the potato without having to read many mis- 
cellaneous sources of information, especially experiment 
station bulletins which, although highly valuable, are 
likely to contain much detail. 

The chapters on breeding and varieties occupy an 
unusually large proportion of the book. This is for the 
reason that these subjects have been treated in potato 
literature much less than methods of culture, and the 
general interest in them has called for this extended 
discussion to meet not only the necessities of the case 
but also the public demand. 

I have been glad to place in the hands of Doctor Bar- 
rus and Mr. Dean the chapters on Diseases and Field 
Methods respectively. These men have had broad ex- 
perience in their lines and are thoroughly competent to 
discuss them. 

The author wishes, also, to acknowledge the valuable 
aid of Professor Herrick in reading the manuscript on 
Potato Insects, and Mr. A. C. Fraser and Mr. J. J. 
Pollock for valuable assistance. 

ARTHUR W. GILBERT. 

Ithaca, New York, 
January, 1917. 



CONTENTS 

CHAPTER PAGES 

I. Acreage, Distribution, Production and Valu- 
ation 1-13 

II. History 14-20 

III. Classification and Botanical Characteristics . 21-46 

Description of the Irish potato — Classification 
of varieties — Important varieties of Iowa and. 
the Central West — Tabulation of varieties — 
Synonyms — Description of typical varieties. 

IV. Potato Breeding ....... 47-85 

Ideals for the potato crop — Use of score card 

— Possibilities of improving the potato — Meth- 
ods of improvement — Improvement of the potato 
by selection — Running out of varieties — Ap- 
pearance of bud sports — Improvement by hy- 
bridization. 

V. Climate, Soils and Rotation .... 86-112 
Factors influencing potato culture — Heat — 
Water requirements — Soil texture — Available 
plant-food — Drainage and soil air — Critical 
period — Type, variety and strain — Diseases — 
General types of potato-growing in the United 
States — Soils — Rotation — Hay plants. 

VI. Manures and Fertilizers ..... 113-132 
Fertilizer practices — Market forms of fer- 
tilizers — Nitrogen — Phosphorus — Potassium 

— Calcium — Sulphur — Applying fertilizers — 
Farm manures. 

vii 



viii Contents 

CHAPTER PAGES 

VII. Planting , . . . 133-159 

Tillage tools — Results of tillage — Planting — 
Hill and drill planting — Planting tools — Hand 
planting — Seed potatoes — Cutting seed. 

VIII. Care of the Growing Crop ..... 160-169 
IX. Potato Insects and Their Control . . . 170-182 
The Colorado potato-beetle — Flea-beetle — 
Blister-beetle ■ — The three-lined leaf-beetle — 
Tortoise-beetles — The potato plant-louse — 
Leaf-hoppers — The potato-stalk weevil — The 
stalk-borer — White grubs — Wire- worms. 

X. Diseases of the Potato 183-205 

Classification of causes of disease — Early 
blight — Late blight — Rhizoctoniose — Fusa- 
rium wilt — Verticillium wilt — Fusarium dry- 
rot — Silver scurf — Potato wart — Common 
scab — Black-leg — Bacteria wilt — Powdery 
scab — Tip-burn — ■ Arsenical injury — Spindling 
sprout — Net-necrosis — Curly dwarf — Mosaic 
leaf-roll — Constitutional degeneracy and other 
weakened conditions of plants. 

XL Control Measures against Diseases . . . 206-225 
Control of curly-dwarf, mosaic and leaf-roll 

— Field inspection — Seed treatment to prevent 
disease — Disease from organisms already in soil 

— Treatment for potato blight — Preparation of 
bordeaux mixture — Other remedies — Disease- 
resistant varieties — Summary. 

XII. Harvesting the Potato 226-236 

Time to harvest — Methods of digging — Pick- 
ing and sorting — Labor and cost of harvesting. 

XIII. Markets, Marketing and Storage . . . 237-258 
Marketing through local dealers — Marketing 
the crop — Grading — Packages — Shipping — 
Early and late potatoes — Markets — Range and 
prices. 



Contents ix 

[ CHAPTER PAGES 

"XIV. Uses of the Potato 259-286 

Use for human food — Quality when cooked — 
Use for starch — Process of starch manufacture 
— Uses of potato starch — Uses for industrial 
alcohol — The manufacture of alcohol from pota- 
toes — Use as stock food — Alcohol slops or resi- 
due — Potato pomace — Poultry food — Dried 
or desiccated potatoes — Potato flour. 

XV. Cost op Growing Potatoes 287-313 

Results of a survey in New York state — Other 
survey results — Cost of hauling. 



LIST OF PLATES 

PLATE FACING PAGE 

I. The potato as first grown in Europe . . 19 

II. Types of potato tubers, as illustrated by the Wis- 
consin Experiment Station . . . . 32 ^ 

III. A plate of smooth potatoes with few and shallow 

eyes — the breeder's ideal . . . 48 ! 

(Photo by Farm Crops Dept., Cornell University) 

IV. Illustration of good shaped potato for table use. 

Variety, Green Mountain . . . .51 
(Photo by Farm Crops Dept., Cornell University) 

V. Typical early and late potatoes. Top, Irish Cob- 
bler (early). Bottom, Rural New Yorker 

(late) 53 ' 

(Photo by Farm Crops Dept., Cornell University) 

VI. Breeding. Each group of four plates represents the 
progeny of a tuber, and each plate is the prod- 
uct of a single hill . . . . . 56 >■ 

VII. Tubers with histories. Upper, influence of growing 
season, showing the second-growth tubers on 
the right compared with the normal uniform 
tubers on the left. Lower, breeding. — The 
immunity and susceptibility of two tuber 
progenies . . . . . . 61 

VIII. Seed potatoes. Top, different ways of cutting. 

Bottom, good and bad types for seed . . 100 



xii List of Plates 

PLATE FACING PAGE 

IX. Potato diseases. Upper tuber, rot caused by late 
blight ; two bottom tubers, net necrosis. Leaf, 
under surface, showing effect of late blight . 190 
(Tuber cuts — Courtesy of Dept. of Plant 
Pathology, College of Agriculture, ■ Cornell 
University) 

(Leaf cut — Courtesy of the Geneva Agricul- 
tural Experiment Station Bulletin 241, Plate 
XII) , 

X. Potato diseases. Top, part of a potato leaf, 
showing spots of early blight. Bottom, 
rhizoctoniose ....... 194 

(Courtesy Dept. of Plant Pathology, College of 
Agriculture, Cornell University) 

XL Potato diseases. Left, powdery scab. Right, 

fusarium dry rot ...... 196 

(Courtesy Dept. of Plant Pathology, College of 
Agriculture, Cornell University) 

XII. Spindling potato sprouts. Upper picture, rhizoc- 
toniose ........ 198 

(Courtesy Dept. of Plant Pathology, College of 
Agriculture, Cornell University) 

XIII. Preparing the bordeaux mixture .... 217 
(Courtesy Dept. of Plant Pathology, College of 

Agriculture, Cornell University) 

XIV. The potato harvest. View in an eastern field . 232 
XV. Combined potato digger and loader . . . 233 

(Photo by W. C. Blake) 
XVI. Potato products 259 



THE POTATO 



THE POTATO 



CHAPTER I 

ACREAGE, DISTRIBUTION, PRODUCTION AND 
VALUATION 

The potato is one of the most widel y cultiva ted of the 
agricultural plants. The esculent tubers, which are devel- 
oped underground on slender leafless shoots or stems, are 
used for food and also industrially. The plant is allied 
botanically to several powerful narcotics, such as tobacco, 
henbane and belladonna, and also to the tomato, egg- 
plant and capsicum. 

The potato comprises about 25 per cent of the food 
of European and English-speaking peoples. Only the 
Oriental peoples exist without it. A greater weight of 
potatoes can be produced to a unit area than any other 
food crop. ' 

The yield in millions of tons of the world's most im- 
portant plants is shown in the following table : 

Table I. — World's Crops of the Most Important Food 
Plants, in Million Tons. Average for 5 Years, 1908- 
1912 

Potatoes 161.0 

Corn 128.38 

Wheat 106.0 

Oats 65.6 

Rice 1 55.6+ 

Rye 57.0 

Barley 33.41 

1 This figure does not represent the rice crop of the world, as statistics 
from certain sections of China are lacking. 
B 1 



2 The Potato 

The average annual production of potatoes in the world 
for the last ten years has been over 5,000,000,000 bushels. 
The production of wheat, corn and oats has been approxi- 
mately 4,000,000,000 bushels each. Potatoes, therefore, 
lead the other crops in total production. 

This immense total world production is generally and 
widely distributed. The six leading countries and their 
average annual production for the years 1911-1913, and 
the average yields an acre for the years 1904-1913, are 
as follows (see Fig. 1) : 

Table II 



Germany . . 
European Russia 
Austria-Hungary 
France . . . 
United States . 
United Kingdom 



Total Production 
in Bushels 



1,698,826,000 
1,258,120,333 
642,149,000 
499,523,666 
348,303,000 
259,482,666 



Average Yield an 
Acre in Bushels 



200.7 
106.4 
134.35 
130.2 
96.5 
210.0 



About 90 per cent of the world's crop is grown in 
Europe, Germany and Russia producing more than half of 
the total crop. The United States produces only about 
one-fifth as much as Germany. This is largely due to 
the fact that the German consumption per capita is about 
two and one-half times as great as ours, and that more 
than 50 per cent of the German crop is used either for 
stock food or for conversion into starch, alcohol or other 
industrial by-products. Potatoes, at present, are used 
very little for these purposes in this country, less than 1 
per cent being so employed. 



Acreage and Value 3 

Table III. — Percentage of World's Potato Crop : Pro- 
duced by the Continents, and Principal Potato-pro- 
ducing Countries. For the Years 1908-1912 



Continents 



Bushels 



Per Cent 
World's Crop 



Europe . . . 
North America 
Asia .... 
South America 
Australia . 
Africa . 



,817,830,200 

425,239,800 

54,329,000 

38,931,000 

13,813,600 

4,793,200 



89.72 

7.92 

1.01 

.73 

.26 

.09 



Principal Countries 



Total Bushels 



1908-1912, 

Per Cent 

World's Crop 



Germany . 
Russia . . . . 
Austria-Hungary 
France . . . . 
United States 



1,624,801,000 

1,209,513,400 

664,538,200 

514,542,200 

346,119,200 



30.25 

22.52 

12.39 

9.58 

6.45 



The cultivation of the potato is now extended over most 
of the agricultural sections of the United States and 
Canada and it is becoming increasingly important as an 
article of human food in this country. It ranks sixth in 
agricultural importance in the United States. 

Table IV. — Relative Value of Crops in the United 
States in Dollars (1908-1912) 

Corn 1,512,780,000 

Hay 768,330,000 

Cotton . . . 724,710,000 

Wheat 666,940,000 

Oats 412,360,000 

Potatoes 209,720,000 

Barley 107,710,000 

Tobacco 94,429,000 

1 Average of world's crop for 1908-1912 = 5,369,590,000 bushels. 



The Potato 




Acreage and Value 5 

The following table illustrates graphically the distribu- 
tion of potato-growing in the United States (see Fig. 2). 

In the United States, New York has led in potato pro- 
duction for the last twenty-five years. The leading states 
and yield to the acre are as follows : 1 

Table V 



State 


Production in 
Millions of 

Bu8HEL8, 

1911-1915 


Yield to 

-iiii. A' KL, 
1906-1915 


Avehaoe Price 
a Bubhel, 
1906-1915 








Centn 


New York 


33.35 


97 


63 


Michigan 


33.27 


94 


59 


Wisconsin 


32.80 


102 


87 


Minnesota 


30.04 


102 


44 


Maine 


25.67 


204 


54 


Pennsylvania .... 


23.13 


85 


08 



In the last few years, Michigan, Wisconsin, Maine and 
Minnesota have been rapidly gaining in production, and 
are now all close rivals of New York. 

For the ten years 1902-1911 inclusive, an average of 
3,230,000 acres was devoted to the potato crop in the 
United States, from which 304,158,000 bushels were pro- 
duced, worth $177,503,000. This comprises only about 
one-sixth of the world's crop. 

Ten states along the northern border, where the climate 
is cooler and the crop is supplied with more moisture, pro- 
duced nearly two-thirds of the potato crop of the United 
States (see Figs. 3 and 4). Potatoes are grown, however, 
in more or less quantity in every state of the Union. 

As the agriculture in the United States becomes more 



1 After Montgomery. 



The Potato 




Acreage and Value 7 

stable and railroad facilities develop, there Is more 

oi a for farm crops to he intensively 

n in certain areas where soil, climate and other factor- 
are best suited to them. This is especially true of a crop 
like corn -.. rheat which Is neither perishable" nor very 
bulky and can be easily shipped. This is becoming 



JZ 02%, 




24 3S% 

Fig. 3. Pe r .ich is 

iced in eael . 2-1911. 

increasingly true of potatoes because of their bulk. 
and partial perishables 

Most of the potatoes raised in the United States are 
still grov •.-. ash crop in relatively small parcels on 

many farms. There is a 1 however, toward the 

■ : pol ■ -. ing centers in widely 
rated of the Unite. State By a careful inspec- 

tion of the map on page 6' one ee that thee 

are located in Aroostook Count;/, Maine, the Xorfok. 

an Shore trucking s of Virginia and Mar viand, 
the Red River Valley of Minnesota and North Dal 
the Ka.7,- Valley of Kansas,, the Greely and Carbondale 
districts v Colorado and the San Joaquin and Sacramento 
valley I ( alifornia. 



The Potato 



MILLIONS OF BUSHELS 



MEW YORK 

MICHIGAN 

WISCONSIN 

MAINE 

MINNESOTA 

PENNSYLVANIA 

OHIO 

IOWA 

ILLINOIS 

COLORAOO 

CALIFORNIA 

INDIANA 

VIRGINIA 

NEBRASKA 

NEW JERSEY 

MISSOURI 

WASHINGTON 

KANSAS 

NORTH OAKOTA 

KENTUCKY 

OREGON 

IDAHO 

VERMONT 

WEST VIRGINIA 

MARYLAND 

SOUTH DAKOTA 

MONTANA 

MASSACHUSETTS 

TENNESSEE 

CONNECTICUT 

UTAH 

NORTH CAROLINA 

NEW HAMPSHIRE 

TEXAS 

ARKANSAS 

OKLAHOMA 

LOUISIANA 

ALABAMA 




| 1909 
2 1899 



Fig 4. Production of potatoes in the different states, 1909 and 1899. 



Acreage and Value 



9 



The following tables from the thirteenth census indi- 
cate the total number of farms in certain states where 
potatoes were grown, the total yield and the total amount 
to each farm. The latter figure shows that the total pro- 
duction on most farms is in excess of the family con- 
sumption : 

Table VI 



State 


County 


Bushels 
to a 

Farm 


County 


Bushels 

TO A 

Farm 


County 


Bushels 

TO A 

Farm 


Mass. 


Berkshire 


128.5 


Hampshire 


112.3 


Hampden 


119.9 


Vt. 


Bennington 


169.2 


Chittenden 


154.5 


Addison 


116.1 


N. J. 


Salem 


636.8 


Monmouth 


643.8 


Gloucester 


389.1 


Del. 


Kent 


44.3 


New Castle 


83.8 


Sussex 


101.4 


W. Va. 


Jackson 


42.9 


Wood 


48.1 


Preston 


43.4 


S. C. 


Beaufort 


39.9 


Charleston 


33.0 


Colleton 


29.4 


Ga. 


Chatham 


189.4 


Thomas 


9.7 


Union 


11.0 


Fla. 


St. John 


183.4 


Hillsboro 


22.1 


Gadsden 


13.7 


111. 


Cook 


161.7 


Madison 


188.6 


St. Clair 


260.9 


la. 


Blackhawk 


92.5 


Grundy 


489.8 


Scott 


358.5 


Mo. 


St. Louis 


167.2 


Buchanan 


127.9 


Ray 


135.6 


Neb. 


Sioux 


134.5 


Douglass 


134.2 


Cherry 


68.6 


Ky. 


Jefferson 


386.5 


Pike 


25.0 


Campbell 


98.9 


Ala. 


Mobile 


109.7 


Jefferson 


20.9 


Dallas 


3.8 


Tex. 


Harris 


58.7 


Cherokee 


32.0 


Cass 


15.3 


Wash. 


Yakima 


365.5 


King 


203.4 


Pierce 


166.7 


Id. 


Ada 


89.6 


Bingham 


802.4 


Lincoln 


120.7 



/v.y i 

Af/ctf, i 
W/5. I 
AW/V£-| 

A7//V/V. 

us. 



I 23*9 % 



2.65% 

2-7/ % 






Z.03% 



S23% 



Fig. 5. Percentage of the improved farm land that was annually 
planted to potatoes in the ten leading states of the United States, 
1902-1911. 



10 



The Potato 



Table VII 



State 



Number 
of Farms 



Total Yield 



Total 

Amount 
to a Farm 



Yield 
to the 
Acre 
prom 
Year- 
book, 
1914 



Northern States 



Massachusetts 
Vermont . . 
New Jersey 




2,946,178 
4,145,630 

8,057,424 




Southern States 



Delaware . . 

West Virginia 
South Carolina 
Georgia . . . 
Florida . . . 



10,836 

96,685 

176,434 

291,027 

50,016 



880,360 
4,077,066 
782,430 
886,430 
856,967 



81.2 

42.1 

4.4 

3.1 

17.1 



96 
98 
85 
81 
95 



Northern Central States East of the Mississippi River 


Ohio 

Illinois 


272,045 1 20,322,984 74.7 
251,872 12,166,091 48.3 


93 
91 


Northern Central States West of the Mississippi River 


Missouri 

Nebraska 


217,044 

277,244 
129,678 


14,710,247 
7,796,410 
8,117,775 


67.7 
20.8 
62.5 


89 

85 
78 


Southern Central States 


Kentucky 

Alabama 

Texas 


259,185 
262,901 
417,770 


5,120,141 
1,128,564 
2,235,983 


19.7 
4.2 
5.3 


92 
80 
50 


Far Western States 


Montana 

Washington .... 
Idaho 


26,214 
56,192 
30,807 


3,240,696 
7,667,171 
4,710,262 


123.6 180 
136.4 170 
152.8 200 



Acreage and Value 



11 



It is not easy to determine the amount of the family con- 
sumption of potatoes. It varies with different regions. 
In a survey of 483 farm families quite widely scattered, 
Funk found the average quantities and values of Irish 
potatoes consumed annually to a person in the following 
table : 

Table VIII 



State 


Irish Potatoes 




Bushels 


Value 


North Carolina 

Georgia . 


1.8 
1.5 
2.7 
5.7 
7.6 
8.6 
5.6 
5.6 
8.0 
9.7 


$2.13 
2.32 


Texas 


3.24 


Ohio 

New York 

Vermont 


4.40 
4.42 
4.31 
2.81 
2.80 
4.17 
3.98 


Average 


5.7 


$3.45 



The average, it will be seen, was 5.7 bushels to a person. 
In the same survey was found an average of 4.6 persons 
in the family, making a total of 26.22 bushels of potatoes 
consumed to a family. Warren l gives the average quan- 
tity of potatoes raised on the farm and used in the house 
on 106 farms in Livingston County, New York, in 1909 
as 50.3 bushels and the average amount to an individual 
as 10.1 bushels. This is much higher than the figures 
Funk obtained in his survey, but even at this high figure, 
it is clearly seen that most farmers have at least a few 
bushels of potatoes to sell. 

1 Warren, G. F. "Farm Management," p. 24. 



12 The Potato 

In a farm management survey of Chester County, 
Pennsylvania, by Spillman * it was found that the propor- 
tion of income from potatoes on 378 farms in that county 
was 8.9 per cent. On these farms, 6 per cent of the 
crop area was devoted to potatoes. "They were found 
on 366 of the 378 farms operated by owners. This crop 
is, therefore, very general in this region, though the acre- 
age of potatoes is usually small. On only seven farms was 
the percentage of potato acreage found to exceed 20 (or 12 
acres)." The farmers of this region grow at least enough 
for home use and usually some for sale. 

The yields to the acre are dependent upon many fac- 
tors, the most important of which seem to be climate 
and soil moisture. Yields to the acre in the United 
States are low as compared with England or Germany. 
The average yields of potatoes to the acre for the years 
1901-1910 inclusive in the United States, Germany and 
Great Britain were 92.7, 200.8 and 200 respectively. 
European countries often grow the large, coarse, heavy- 
yielding sorts for stock-feeding or for use in the arts, which 
accounts for some of the difference in average yields. 

In the United States, the average yield to the acre is 
higher in Maine than in any other state. The average 
yield in the other states is usually 90 bushels or less. 

Very large yields in the United States, however, are 
not unheard of. A yield of 700 bushels to the acre in 
Maine and the other potato-producing areas is not un- 
common in very favorable^ seasons. Macoun, in speak- 
ing of the possibilities of the potato, makes note of the 
highest recorded yield of potatoes in this country. These 
were grown by Mrs. Selinda E. Jones of Chautauqua 

1 Spillman, Dixon and Billings. "Farm Management Practice of 
Chester Co., Pa.," p. 26. 



Acreage and Value 13 

County, New York, in the Women's National Potato 
Contest of 1888. She grew the White Elephant variety 
on one-twentieth of an acre at the rate of 1061 bushels to 
the acre. 

In the United States the average yield of potatoes from 
one plant is about one-half pound. Some plants of 
Early Ohio have been known to yield thirteen tubers 
weighing 2| pounds, and others of the same variety to 
produce three tubers weighing \ an ounce. The former 
yield is 80 times the latter. Some English experiments 
have produced twenty pounds of tubers to a plant, as 
many as 150 tubers being set on one plant. 

The climate of Canada is well suited to the produc- 
tion of potatoes. The cool summers produce a yield to 
the acre that compares very favorably with the best 
regions of the United States. The average number of 
acres devoted to this crop for the years 1910-13 was 
476,000, upon which an average yield of 152.46 bushels 
to the acre was secured, making an average total yield 
for the four years of 72,569,000 bushels. 

In the five fiscal years 1910-14, Canada exported an 
average of 1,451,990 bushels of potatoes each year, of 
which 376,406 bushels were sent to the United States. 



CHAPTER II 
HISTORY 

The early history of the potato is a matter of some 
doubt among historians, but all are agreed that it came 
originally from the high lands of Peru and Chile, where it 
is still found growing wild. 

The Spaniards first discovered the potato in the neigh- 
borhood of Quito, Ecuador, where it was cultivated by the 
natives. According to Pedro Cieca de Leon, who seems 
to have made first written mention of the potato in his 
"Spanish Chronicles of Peru" (1550), the inhabitants 
subsisted largely on maize and what they called "papas" 
and "quinua." The former is the Indian name for 
potato and the latter "is a plant about the height of a 
man and has leaves like the blite of Mauritania, and a 
small seed either red or white in color, from which is 
prepared a drink, and a food comparable to our rice." 

Potatoes were used by the aborigines in place of bread, 
and were also dried in the sun to preserve them. They 
were usually cooked, but often made into flour. There 
was evidence of long-continued practice of cultivation, 
however crude. The potato, however, was and still is 
wild in the mountainous regions of Chile and Peru. 

The potato was probably carried to Spain by explorers 
in the sixteenth century. There is no definite record of 
this first importation, but Rose believes that it was as 

14 



History 15 

early as 1533 or 1535, at the time of the conquest of Peru 
by the Spaniards. Hieronymus Cardan, a monk, is 
supposed to have been the first to introduce it from 
Peru into Spain, and from thence it passed quickly into 
Italy, Austria, Germany, Switzerland, Belgium and 
France. The first figures and detailed description of it 
in its new home in continental Europe are those of Clusius 
in 1601 in his " Rariorum Plantarum Historia," although 
Bauhin in his " Phytopinax," printed in Basel in 1596, 
described it and gave it the Latin name or characteriza- 
tion, Solanum tuberosum esculentum.. (See Plate I.) 

The date and method of introduction of the potato 
into North America are not definitely known, but it was 
probably introduced by Spanish voyagers and at some- 
time before 1585, for it is clearly recorded that its first 
introduction was made into England by colonists from 
Virginia in 1586 under the patronage of Sir Walter 
Raleigh. 

"It seems to me most likely," says De Candolle, "that 
some inhabitants of Virginia — perhaps English colo- 
nists — received tubers from Spanish or other travelers, 
traders or adventurers, during the ninety years which 
had elapsed since the discovery of America. Evidently, 
dating from the conquest of Peru and Chile, in 1535 to 
1585, many vessels could have carried tubers of the potato 
as provisions, and Sir Walter Raleigh, making war on 
the Spaniards as a privateer, may have pillaged some 
vessel which contained them. This is the less improbable, 
since the Spaniards had introduced the plant into Europe 
before 1585." 

At the discovery of America, we are told by Humboldt, 
the plant was cultivated in parts of western South 
America from Chile to Colombia but not in Mexico, and 



1(1 The Potato 

there is n<> account of its being found wild in other parts 
of North America. 

From 15X5 or 1586, potato tubers were brought from 
what is now North Carolina to Ireland on the return of 
the colonists sent out by Sir Walter Raleigh, and were 
first cultivated on Sir Walter's estate near Cork. This 
was some years later than, their introduction into conti- 
nental Europe. 

In l()29, Parkinson in his " Paradisus," in which he gives 
an indifferent figure of the potato under the name of 
Papas seu Battatas Virginianorum, adds details as to the 
method of cooking the tubers which seems to indicate 
that they were still luxuries. 

The cultivation of the potato in England made little 
progress for many years. It is said that in, the time of 
.lame; the First, they were so rare as to cost two shillings 
a, pound, and are mentioned in 1019 among the articles 
provided for the royal household. In 1 633, when their 
valuable properties had become more generally known, 
they were deemed worthy of notice by the Royal Society, 
which took measures to encourage their cultivation and 
for introduction into Ireland, especially as a safeguard 
against famine, but their cultivation has become general 
only within the last one hundred years. 

John Gerard received souk; tubers of the potato from 
Virginia, and planted them in his garden. He gave a 
careful description of them in his "Herbal," the first 
edition of which was published in London, in 1597. In a 
later edition (1636) he pictures them by means of a wood- 
cut (see Fig. 6). He was so proud of these plants that 
he was represented in his portrait at the beginning of 
the work holding a flowering branch of the plant in his 
hand. 



History 



17 



It should be noticed how closely the description of the 
potato at this early date corresponds with the plant as 
grown to-day. He says: "Virginia potato hath many 
hollow, flexible branches trailing upon the ground ; 
these are square, 
uneven, knotted or 
kneed in sundry 
places at certaine 
distan'-' : from 
the which knots 
Cometh forth one 
great leafe made of 
divers leaves, some 
smaller arid other 
greater, set to- 
gether upon a fat 
middle rib by 
couples, of a swart 
green colour tend- 
ing to redness ; the 
v/ hole leaf resem- 
bling those of the 
Winter-Cresses, but 
much larger ; in 
taste at the first 
like grasse, but af- 
terwards sharp and 
nipping the tongue. 
Prom the bosorne of which leaves come forth long round 
slender foot stalkes, whereon grew very faire and pleasant 
floures, made of one entire whole leafe, which is fold'-' I or 
plaited in such strange sort, that it seems to be a floure 
made of five sundry small leaves, which cannot easily be 
c 





Fia. ''>■ Copy of the engraving of the Vir- 
ginian potato i" Gerard's "Herbal" — printed 
in 1636 



18 The Potato 

perceived, except the same be pulled open. The whole 
floure is of a light purple colour, striped downe the middle 
of every fold or welt with a light show of yellownesse, as 
if purple and yellow were mixed together. In the middle 
of the floure thrusteth forth a thicke flat point all yellow 
as gold, with a small sharpe greene pricke or point in 
the midst thereof. The fruit succeeds the floures, round 
as a ball, of the bigness of a little Bullesse or wild plumme, 
green at first, and blacke when it is ripe, wherein is con- 
tained small white seed lesser than those of mustard; 
the root is thick, fat, and tuberous, not much differing 
either in shape, colour or taste from the common potatoes, 
saving that the roots hereof are not so great nor long; 
some of them are as round as a ball, some oval or egge- 
fashion, some longer and others shorter; the knobby 
roots are fastened unto the stalkes with an infinite num- 
ber of threddy strings. It groweth naturally in Americus 
where it was first discovered, as reporteth Clusia, since 
which time I have received roots hereof from Virginia, 
otherwise called Norembega, which grow and prosper in 
my garden as in their own native country. The leaves 
thrust forth on the ground in the beginning of May ; the 
floures bud forth in August, the fruit is ripe in Septem- 
ber. The Indians call this plant pappas, meaning roots, 
by which name also the common potatoes are called in 
those Indian countries. We have its proper name men- 
tioned in the title 'Potatoes of Virginia.' Because it 
hath not only the shape and proportion of potatoes but 
also the pleasant taste and vertues of the same, we may 
call it in English, Potatoes of America or Virginia." 

In 1769, the grain crops of France were a failure, threat- 
ening a national famine. Parmentier, a Parisian chemist, 
recommended the use of potatoes as food to take the 




Plate I. — The potato as first grown in Europe. 



History 19 

place of the grain crops. He had been a member of the 
medical staff of the French army in 1758, during the war 
in Hanover, and had been taken prisoner. During his 
five years in prison his principal food consisted of potatoes, 
which were then grown almost exclusively as food for 
animals. The dire need of food in France inspired him 
to write a book called a "Treatise on Certain Vegetables 
that in Times of Necessity can be substituted for Ordinary 
Food." This book was received with ridicule even 
though it received a certain amount of support from the 
Paris Agricultural Society. By persistent efforts, Par- 
mentier was granted a small patch of land on which to 
experiment with his potatoes. The king ordered the 
plot to be guarded by a cordon of troops which excited 
the curiosity of the people. On August 24th, the king's 
fete-day, he presented the king with a basket of tubers 
and a bouquet of the blossoms. These were worn by the 
king and queen, who also ate the cooked tubers. They 
were found to be very palatable and soon became one of 
the foods of the French people. 

During the seventeenth century, the potato gradually 
became, from a botanical curiosity cultivated only by 
collectors of new plants, one of the staple garden and field 
crops. Its cultivation as a field crop became somewhat 
common in Germany soon after 1772, when the grain 
crops failed and potatoes were used as a substitute. The 
quality was very poor, however, and even though they 
were enormously productive, their use was restricted 
largely as food for domestic animals and they were used as 
human food only when necessary as a substitute. By 
the latter half of the eighteenth century, it was exten- 
sively cultivated and recognized as one of the regular 
crops throughout the temperate regions of Europe and 



20 The Potato 

America, so that Henry Phillips (1822), who published a 
detailed account of the potato and its culture, was able 
to cite a single grower who planted 300 acres annually. 

In Ireland, they were used very extensively as human 
food. By 1840 they had largely replaced the cereals and 
similar food crops because their yield in weight exceeded 
by twenty to thirty times the yield of wheat, barley or 
oats on an equal amount of land. Dependence upon a 
single crop for food, however, became disastrous for the 
Irish. The potato blight which appeared in the United 
States in 1845 devastated Ireland in 1846 and caused 
a widespread famine. It is conservatively estimated 
that 600,000 persons died during the two years 1846 and 
1847 for want of food or from diseases caused by a meager 
diet of unhealthy and unnutritious food. By 1848 the 
plague had practically ceased. 

REFERENCES 

Campbell, W. H. W. The Father of the Potato. Cosmopolitan, 

Vol. II, pp. 191-192. 1886. 
De Candolle, Alphonse. Origin of Cultivated Plants. 1-468, 

N. Y., 1892. 
Del'Ecluse (orCLUSius). Rariorum Plantarum Historiae, 1601, lib. 
Gerard. Herbal. 1597, p. 781, with illustration. 
Heckel, E. The Origin of the Cultivated Varieties of the Potato. 

Rev. Sci. (Paris), 50: 1912, II, No. 21, pp. 641-646. 
Henslow, Geo. The Origin and History of Our Garden Vegetables 

and Their Dietetic Values. II. Roots + tubers (cont.). 

Roy. Hort. Soc. Journ., 36: pp. 345-346, Figs. 120- 

121* (1910-1911). 
Rose, Ernest. Histoire de la pomme de terre traitee aux points de 

vue historique, cultural et utilitaire. 1-464 Par. 1898. 
Sabine, J. On the Native Country of the Wild Potatoes. Trans. 

Hort. Soc. London, Vol. V, pp. 249-259. 1824. 



CHAPTER III 

CLASSIFICATION AND BOTANICAL CHARAC- 
TERISTICS 

The common or Irish potato is known botanically as 
Solarium tuberosum. This name was first applied to it 
by Bauhin in his "Phytopinax" in 1596 (page 15) and 
later adopted by Linnaeus. In the same family (Solana- 
cese) are many other plants of economic importance, as 
tomato, eggplant, tobacco, belladonna, henbane and cap- 
sicum or red-pepper. 

Baker has reviewed the tuber-bearing species of Solanum 
from a systematic point of view as well as that of geo- 
graphic distribution. Out of twenty so-called species he 
considers six to be really distinct, while the others are 
synonymous or trifling variations. The six admitted 
tuber-bearing species are S. tuberosum, S. Maglia, S. Com- 
mersonii, S. Cardiophyllum, S. Jamesii and S. oxycar- 
pum. See also "Standard Cyclo. Hort." VI, 3181. 

The following descriptions of species have been taken 
from Baker's "A Review of Tuber-bearing Species of 
Solanum" — Linnsean Soc. Journ. Bot., XX: pp. 489- 
507, pis. 

Solanum tuberosum, Linn. — Stems stout, erect, much branched, 
1-2 feet long, slightly hairy, distinctly winged on the angles. Leaves 
1-2 feet long, slightly hairy, with 7-9 finely pilose oblong acute leaf- 
lets, the side ones stalked and unequally cordate at the base, the 1-2 
lowest pairs much dwarfed, petiole about 1 inch long. Numerous 
small leaflets between larger ones. Flowers in compound terminal 
cymes with long peduncles. Corolla wheel shaped, dark lilac, 

21 



22 The Potato 

nearly 1 inch in diameter. Calyx hairy, |-| inch long, with teeth 
as long as or a little longer than the campanulate tube. Berry 
globose, less than an inch in diameter, smooth. Native of Chile 
and Ecuador. 

Solarium Maglia, Schlecht. — Stems stout, erect, much branched, 
1-2 feet long, strongly winged on angles, slightly hairy. Leaves 
6-9 inches long, larger leaflets 5-7, ovate acute, 2-3 inches long, side 
ones stalked, unequally cordate at base. Flowers in compound 
cymes; pedicles downy. Corolla white, subrotate, f to 1 inch in 
diameter. Style twice as long as the stamens. Fruit not seen. 

Solarium Commersonii, Dunal. — Stems shorter and more slender 
than in S. tuberosum. Leaves 5-6 inches long, with a naked petiole 
1-1 \ inches long; 5-9 oblong acute leaflets, the terminal one much 
the longest; the rachis entirely without any of the small leaflets 
interspersed among the large ones. Flowers in lax compound cymes. 
Calyx f-j inch long. Corolla pale lilac or white. Anthers orange- 
yellow. Style distinctly exserted beyond the anthers. South 
America. 

Solarium cardiophyllum, Lindley. — Of the same general habit as 
S. tuberosum. No small leaflets interspersed amongst the large 
ones. Whole plant quite glabrous. Foliage very dark green. 
Leaflets 5, large, ovate acute. Flowers in compound cymes. Calyx 
glabrous. Style scarcely longer than the stamens. Mountains of 
Central Mexico at an elevation of 8000-9000 feet. 

Solarium Jamesii, Torrey. — Minute globose tubers. Leaves dis- 
tinctly petiolate, with 5-9 oblong acute leaflets ; no smaller leaflets 
interspersed amongst the longer ones. Cymes few flowered. Co- 
rolla white. Fruit globose. Mountains of southwestern United 
States and Mexico. 

Solanum oxycarpum, Schiede. — Tubers minute. Leaflets 5-9, 
oblong lanceolate, with no smaller leaflets interspersed amongst the 
larger ones. Cymes few flowered. Fruit ellipsoidal. 

DESCRIPTION OF THE IRISH POTATO 

The common potato owes its value to the peculiar 
habit of developing underground slender leafless shoots 
or branches which differ in character and office from 
the true roots, and gradually swelling at the free end 



Description and Classification 23 

produce the tubers (potatoes), which are the common 
vegetable food. The nature of these tubers is further 
rendered evident by the presence of "eyes" or leaf- 
buds, which in due time lengthen into shoots and form 
the haulm or stems of the plant. Such buds are not, 
under ordinary circumstances, formed on roots. This 
budding of the tubers furnishes an efficient method 
of propagation, independent of seed production. Starch 
and other matters are stored up in the tubers, as in the 
seed, and are rendered available for the nutrition of the 
young shoots. When grown under natural circumstances, 
the tubers are relatively small, and close to the surface 
of the soil, or even lie upon it. In the latter case, they 
become green and have an acrid taste, which renders them 
unpalatable to human beings, and as poisonous qualities 
are produced similar to those of many Solanacese, they 
are unwholesome. Hence the recommendation to keep 
the tubers in cellars or pits not exposed to the light. 
Among the 900 species of Solanum, less than a dozen 
have this property of forming tubers. The production 
of small green tubers on the haulm, in the axils of the 
leaves of the potato, is not very infrequent, and affords 
an interesting proof of the true morphological nature of 
the underground shoots and tubers. This phenomenon 
follows injury to the phloem in the lower parts of the 
stem, preventing the downward flow of the elaborated 
sap. 

CLASSIFICATION OF VARIETIES. PLATE II 

For the sake of convenience, the many varieties which 
are now on the market may be classified. No one classi- 
fication, however, will be adequate to cover all conditions. 
Varieties differ somewhat from one part of the country 



24 The Potato 

to another. Most standard varieties have many syn- 
onyms which make the whole matter more confusing. 
The frequent appearance of new names for old varieties 
is as much the fault of the grower as it is of the seedsman. 
There is a strong demand for new things. The seeds- 
man attempts to meet this, but most of our seedsmen 
are professedly not originators of new varieties, and the 
supply of strictly new varieties must, of necessity, be 
very limited, hence the demand is met by changing the 
name of some old variety and giving extensive advertis- 
ing under its new name. The gullible grower accepts 
the dose, pays the price for the supposedly new article 
and is satisfied until he learns that it is nothing new and 
then he turns around and repeats the process again. 

The number of named varieties is so large that the 
chances of finding something far superior are very slight. 
However, it is not at all impossible to find such a variety if 
one has the patience to look for it or the skill to produce it. 
However, for the average grower, it is much better to stick 
to the old standard sorts which are recognized in the mar- 
ket. If better varieties are demanded, it is wiser, in gen- 
eral, to start with standard varieties which have already 
reached some degree of perfection and improve them. 

The potato is very susceptible to differences in soil 
and climate, and varieties often lose their distinguishing 
characteristics when grown under what might be con- 
sidered unusual environment. There has also grown up, 
of course, a wide range of opinion as to what the standards 
of certain varieties are. The standard of a variety in 
one locality may be very different from the accepted 
standard of that same variety in another locality. The 
introduction of new varieties which may be but slight 
variations from the old sorts has still further complicated 



Description and Classification 25 

the situation. Moreover, many so-called new varieties 
are merely the old varieties under a new name. But on 
the whole, the old standard varieties may be recognized 
fairly accurately. 

Potatoes may be classified according to the shape of 
the tubers. "Tubers are not always of the same form; 
three moderately distinct and fairly constant types are 
prevalent, namely, (1) round, (2) oval and (3) kidney 
shapes. The round type is somewhat spherical and has 
fewer internodes and 'eyes' than the oval or kidney- 
shaped potatoes. The kidney potatoes are thickest at 
the stem or basal end and taper gradually at the apex 
or seed end, while the oval varieties are thickest in the 
middle and taper towards both ends (see Fig. 7). These 
differences are sufficiently marked and constant for a 
comparison of the varieties in cultivation." — Percival. 

Important varieties of Iowa and the Central West 

C. L. Fitch, 1 of the Iowa State College, made a thor- 
ough trial for a series of years of all varieties of commercial 
importance in the United States and Europe. He made 
also a canvass in person and by letter of the markets 
of the United States. The result was that only a few 
varieties were found to be of much commercial impor- 
tance. He lists the following varieties as being the most 
valuable in the United States in order of their importance : 

1. Rural 5. Irish Cobbler 

2. Green Mountain 6. Bliss Triumph 

3. Early Ohio 7. Peerless (Pearl) 

4. Burbank 

1 Fitch, C. L. "Identification of Potato Varieties." Iowa Extension 
Bui. 20 (1914). 



26 



The Potato 






Description and Classification 27 

Fitch says that the varieties Rural, Early Ohio and 
Irish Cobbler are the outstanding varieties of Iowa. In 
regard to the others, he makes the following comments : 

"The following are grown in Iowa to a greater or less 
degree or reach our markets. 

" Green Mountain, the second most important variety 
in the United States, and a second best late sort for Iowa. 

" Burbank, still the standard of the U. S. Government 
for market quotations, formerly important in Iowa, and 
at some seasons still important in the supply of her cities. 

" Peerless or Pearl, by test at Ames, ranking among the 
best late sorts, and often coming into her markets from 
Colorado or Wisconsin. 

"Bliss Triumph, sometimes grown in Iowa for very early 
use, and extensively grown in the South for the supply 
of the early markets of Iowa and the northern states." 

William Stuart of the United States Department of 
Agriculture has recently made a very comprehensive and 
admirably arranged classification of potatoes. His bulle- 
tin contains not only a valuable key, but a careful descrip- 
tion of our standard varieties of potatoes and points out 
many unnecessary synonyms. The reader is referred 
to this bulletin for this storehouse of information on 
potato varieties. 

Stuart gives the following classification key : 

Stuart's classification 

Group 1. — Cobbler. 

Tubers : Roundish ; skin creamy white. 

Sprouts : Base, leaf scales and tips slightly or distinctly tinged 

with reddish violet or magenta. In many cases the color is 

absent. 
Flowers : Light rose-purple ; under intense heat may be almost 

white. 



28 The Potato 

Group 2. — Triumph. 

Tubers : Roundish ; skin creamy white, with more or less numer- 
ous splashes of red, or carmine, or solid red; maturing very- 
early. 

Sprouts : Base, leaf scales and tips more or less deeply suffused 
with reddish violet. 

Flowers : Very light rose-purple. 

Group 3. — Early Michigan. 

Tubers : Oblong or elongate-flattened ; skin white or creamy 
white, occasionally suffused with pink around bud-eye cluster 
in Early Albino. 

Sprouts : Base light rose-purple ; tips creamy or light rose-purple. 

Flowers : White. 

Group 4. — Rose Group. 

Tubers : Elongated or oblong, usually flattish at the center and 
tapering gradually toward each end ; stem and seed end rather 
blunt. Skin smooth, flesh color. Flesh creamy white, some- 
times streaked with red. 

Sprouts : Rather long, medium thick, and usually clearly tinted 
with rose-lilac. 

Group 5. — Early Ohio Group. 

Tubers : Round-oblong with full, rounded seed and stem ends. 

Eyes numerous and rather shallow. Skin or flesh light pink 

with a deeper color around the eyes. 
Sprouts : Short, much enlarged at the base, color varying from 

carmine-violet to violet-lilac or magenta-lilac. 

Group 6. — Hebron Group. 

Tubers : Elongated, somewhat flattened, with rather blunt ends, 
occasionally spindle shape. Eyes numerous. Skin creamy 
white, more or less clouded with flesh color or light pink. 

Sprouts : Very similar to those of the Early Rose Group. 



Description and Classification 29 

Group 7. — Burbank Group. 

Tubers : Long, cylindrical or slightly flattened in shape. Eyes 
numerous and rather shallow. Skin white to dull white, 
smooth to glistening, or sometimes russeted. 

Sprouts : Base creamy white or faintly tinged with magenta. 

Flowers : White. 

Group 8. — Green Mountain Group. 

Tubers : Broadly roundish-flattened to distinctly oblong-flat- 
tened ; ends usually blunt, especially the seed end. Eyes rather 
shallow. Skin dull creamy white, more or less netted. 

Sprouts : Rather short and stubby. White or faintly tinged. 

Flowers : White. 

Group 9. — Rural Group. 

Tubers : Round-flattened to broadly roundish — oblong or dis- 
tinctly oblong. Eyes few; very shallow. Skin creamy white 
and occasionally netted. 

Sprouts : Short, base enlarged, dull white. 

Flowers : Of fair size. Central portion of corolla deep violet- 
purple, shading to a lighter tone toward outside edge. 

Group 10. — Pearl. 

Tubers : Round-flattened to heart-shape flattened, usually heavily 

shouldered ; skin dull white, dull russet, or brownish white in 

section 1 or a deep bluish purple in section 2. 
Sprouts : Section 1 — base, leaf scales and tips usually faintly 

tinged with lilac ; section 2 — base, leaf scales and tips vinous 

mauve. 
Flowers : White. 

Group 11. — Peachblow. 

Tubers : Round to round-flattened or round-oblong ; skin creamy 
white, splashed with crimson or solid pink ; eyes usually bright 
carmine. Includes some early-maturing varieties. 

Sprouts: Base, leaf scales and tips more or less suffused with 
reddish violet. 

Flowers : Purple. 



30 The Potato 

Group types according to Fitch 

Group 1. — Rural. 

Tuber shape : Wide and flat types when at best. Ends rounded 

much like stem and usually not recessed. (See Fig. 7.) 
Tuber and eye color : Blinds, white. First sprouts yellow or 

waxy white with bluish violet tips which change, on exposure 

to light, to dark or dull purple. 
Root stubs : Yellowish white ; free from purple. 
Stem : Erect and touched with brownish purple. 
Foliage : Green, darkened by the purple, and in state much more 

acrid than "all-green" foliage. 
Blossom : Bluish violet-white. 

Group 2. — Early Ohio. 

Tuber shape : Somewhat flattened and slightly tapering, with 

stem end a least bit recessed. Eyes are unevenly distributed 

and numerous. (See Fig. 7.) 
Tuber and eye color : Skin brownish pink, almost white to red, 

changing, on long exposure to light, to a weathered gray brown. 

First sprouts are white or greenish white with lilac tips. 
Foliage : Medium green. 
Blossoms : Lilac-white. 

Group 3. — Irish Cobbler. 

Tuber shape : The finest type is flat and wide like good Rurals 
but there is a very distinct round, rough, deep-eyed type formed 
in poorer conditions. In some cases large types are pear 
shaped and rough like the largest Rurals and may combine 
the pear shape with the heavy eyebrow types of the Rural. 

Tuber and eye color : Skin smooth yellowish white, changing in 
the light to dull olive-green with a suggestion of blue. Blinds, 
white. Sprout-leaves, hairy, light green. 

Blossoms : Pink with white tips on petals. White blossoms not 
found on Cobblers. 

Group 4. — Green Mountain. 
Tuber shape : The waisted or dumb-bell type is characteristic. 
Stem end somewhat recessed. (See Fig. 7.) 



Description and Classification 31 

Tuber and eye color : A fine smooth and quite brown netting is a 

feature of many of the tubers. An "all-white" variety. 
Foliage : Bright green. 
Blossoms : White. Buds yellow. 

Group 5. — Burbank. 

Tuber shape : Long, largest at center. Best type, shorter, wide, 

and flattened. Poor type, spindle shaped. Stem end flush. 

Eyes shallow or flush. In poor conditions very subject to knots. 

(See Fig. 7.) 
Tuber and eye color : Blinds, white. Skin white changing in 

light to greenish gray brown. First sprouts white with light 

green tips. 
Foliage : Bright green. 
Blossoms : White. Buds yellow. 

Group 6. — Peerless or Pearl. 

Tuber and eye color : Skin, white, or if ripened well, brownish 
white, coarsely cracked. Skin turns dull green in light. (See 
Fig. 7.) 

Blossoms : White, when borne. Buds, white or greenish white. 

Stem and foliage : Vigorous, bright green. 

Group 7. — Buss Triumph. 

Tuber shape : More or less roughly globular, recessed stem. 
Large tubers somewhat oval or nosy. (See Fig. 7.) 

Tuber and eye color : Pink to red-brown skin changing in light 
to grayish red brown. Blinds, pink to red brown. Sprout- 
leaves, dark apple-green. 

Groups according to Kohler 

Group 1. — Tuberosum Group. 

Characterized by foliage of the wild Solanum type. Tubers of 
varying shape, usually with rather deep eyes; below medium 
in size. 

Foliage relatively resistant to disease. 



32 The Potato 



Group 2. — Rural Group. 



Rural New Yorker is the type of the group. Tubers character- 
istically short, smooth and flattened. Skin white. Eyes 
generally shallow. 



Group 3. — Leo Group. 

Plants upright in habit ; little or no purple in stems. Tubers 
roundish or somewhat elongated with uneven surface. 



Group 4. — Woltman Group. 

Plants medium erect; foliage fairly dense. Tubers similar to 
those of Leo group. Group not very well defined. 



Group 5. — Endurance Group. 

Plants very recumbent ; leaves pure green. Tubers light in color ; 
elongated to medium in length. 



Group 6. — Factor Group. 

Plants fairly erect, with dense foliage. Tubers generally roundish 
or short elliptical ; comparatively even surface. 



Group 7. — Sharpe's Express. 

Plants moderately erect; foliage dark green. Tubers rounded 
or slightly elongated and surface comparatively even. Flowers 
white. 



Group 8. — Green Mountain Group. 

Plants medium upright ; stem free from purple. Tubers medium 
in length with a tendency toward oblong form; white and 
slightly netted skin. Eyes sunken somewhat. 



STANDARD TYPES 



l.'NDESIRABLE rvi'l.s 




TYPICAL BURBANK 




TYPICAL EARLY 






LATE PRIDE TYPES OF LOW MARKET STANDARD 

BURBANK GROUP 




COLORED TYPES COMMON! Y V'OUN'D IN MIXED CAR LC)TS 

ROSE CROUP 







LARGE COARSE KURA1S 'vVillCH ARE OFF-TYPE 

RURAL GROUP 



Plate II. — Types of potato tubers, as illustrated by the Wisconsin 

Experiment Station. 

A careful selection of seed for a few years will gradually eliminate these 

undesirable types. 



Description and Classification 33 

Group 9. — Michigan Group. 

Michigan variety typical of the group. Tubers somewhat elon- 
gated ; skin fairly smooth. A composite group with char- 
acters not well defined. 

Group 10. — Ohio Group. 

The Early Ohio is typical of this group. Tubers oval in shape 
and only slightly compressed ; eyes numerous and usually 
shallow. Surface quite even. 

Group 11. — Cobbler Group. 

Plants upright in habit. Tubers white, pink or red ; variable 
in shape and size. 

Groups according to Mil-ward 
Group 1. — Round White Group. 

Tubers : round to oval and slightly flattened. Surface generally 

netted. Skin white and flesh white. 
Flowers : white or purple. 

Group 2. — Long White Group. 

Tubers : Long oblong in shape and sometimes flattened. Skin 
and flesh white. 

Tabulation of varieties 

The varieties of potatoes mentioned and described by 
Stuart, Milward, Kohler and Fitch have been brought 
together in one table for convenience. Each variety so 
far as possible has been classified by naming the group 
into which it has been placed by one or more of the authors 
named. In this way, it is easy for any person to get an 
idea of a variety if he is unfamiliar with it by referring 
to the description of the group into which the variety is 
placed : 



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Woltman 



Description and Classification 43 

Synonyms 

Frequently potatoes belonging to well-recognized va- 
rieties are renamed and sold as distinctly new sorts. 
This practice may be due to the fact that the seedsman, 
or the grower, is not familiar with all the standard va- 
rieties ; or it may be a fraudulent attempt to induce the 
farmer to pay a high price for seed of a supposedly new 
and superior variety. Then, too, the same type may 
arise in different parts of the country at about the same 
time and be given different names in each locality. Be- 
cause of these conditions we often have one variety mas- 
querading under a number of different trade names. It 
is desirable that a single name be chosen for each distinct 
type, and that that name alone be used to designate 
tubers of the standardized type. The following list of 
synonyms, adapted from Stuart, may be found helpful 
in straightening out variety names : 

Synonym Preferred Name 

Acme Early Acme 

Black Mercer Black Chenango 

Bliss Triumph Triumph 

Blue Noses Mercer 

Boston Market Early Sebec 

Bresee's No. 2 Bresee's Prolific 

Bresee's No. 4 King of the Earlies 

Bresee's No. 6 Peerless 

Bruce's White Beauty White Beauty 

California Russet Russet Burbank 

Chenango Mercer 

Chenango White Mercer 

Early Bovee Bovee 

Early Henry Early Shaw 

Early Hunt Triumph 

Early Pinkeye Dykeman 



44 



The Potato 



Synonym 

Early Sunlight 

Early Victor 

Early Wenwell 

Ensign Bagley 

Farmer Hasting 

Improved Early Rose 

Improved Manistee 

Junior Pride 

Knowles's Big Cropper 

La Plata Red 

Late Hoosier 

Lookout Mountain 

Maine Rose 

Merino 

Meshanock 

Mashannocks 

Nephannocks • 

Neshannocks 

New Blush 

New Minister 

Nishenock 

Page's Extra Early Surprise 

Peachblow 

Peachblow 

Philadelphia 

Pride of the South 

Queen of the West 

Red Bliss 

Red Mercer 

Red Six Weeks 

Rose No. 4 

Round Pinkeye 

Rural New Yorker (No. 1) 

Rural Russet 

Six Weeks 

Spanish 

Stray Beauty 

Vermont Champion 



Preferred Name 

Sunlight 

Victor 

Wendell 

Clark's Pride 

Farmer 

Early Rose 

Early Manistee 

White Triumph 

Knowles 

Long Red 

McCormick 

McCormick 

Early Maine 

Long Red 

Mercer 

Mercer 

Mercer 

Mercer 

Rural Blush 

Minister 

Mercer 

Early Surprise 

Jersey Peachblow 

Western Red 

Mercer 

White Triumph 

Maggie Murphy 

Triumph 

Long Red 

Triumph 

Spaulding No. 4 

Dykeman 

Carman No. 1 

Late Petoskey 

Early Six Weeks 

Long Red 

Triumph 

Champion 



Description and Classification 45 

Synonym, Preferred Name 

Weld's Jumbo Jumbo 

White Bliss Pride of the South 

White Chenango Mercer 

White Early Ohio White Ohio 

White Elephant Late Beauty of Hebron 

White Meshannock White Mercer 

White Triumph Pride of the South 

Willard Seedling Willard 



DESCRIPTION OF TYPICAL VARIETIES 

Below are given brief descriptions of the more popular 
varieties. These descriptions have been taken largely 
from Stuart : * 

Burbank. — Originated by Luther Burbank in 1873 ; claimed to 
be a seedling of the Early Rose. Season medium late. Tubers 
large, round, long ; eyes shallow, but rather numerous ; skin nearly 
smooth, white; flesh firm, fine grained, of excellent flavor when 
cooked. 

Carman No. 1 (Rural New Yorker No. 1). — Originated by 
E. S. Carman in 1889. Seedling of other seedlings. Season medium. 
Very few, shallow eyes; quality excellent ; flesh white. Vines very 
stocky. 

Country Gentleman. — Originated by G. W. P. Jerrard Co. Sea- 
son medium late. Vines of medium vigor and spreading habit; 
flowers white. Tubers long, cylindrical; eyes medium; skin light 
buff; flesh white. 

Early Rose. — Originated by Albert Bresee in 1861. Season 
early. Vines stout, erect; leaves large. Tubers quite smooth; 
nearly cylindrical, tapering toward each end; eyes shallow; skin 
thin, tough, and of a dull blush color ; flesh white, solid, brittle. 

Green Mountain. — Originated by O. H. Alexander in 1878. 
Claimed to be a seedling for a cross between Dunmore and Excel- 
sior. Season medium late. Vines vigorous, with dark green 
foliage. Tubers short and chunky, flattened, not very regular; 

1 Stuart, Wm. U. S. D. A., Prof. Paper, Bui. 176, 1915. 



46 The Potato 

eyes sometimes considerably depressed; skin nearly white; flesh 
fine grained. 

Irish Cobbler. — Of unknown origin. Season extra early. 
Tubers nearly round, large ; eyes good ; skin russet, finely netted ; 
flesh white. Similar or identical with variety Eureka. 

Pearl, Midseason. — Vines strong, medium to large ; stems me- 
dium dark green, rather stocky ; erect at first, bending over as the 
season advances. Leaves large, flat, medium dark green. Flowers 
white. Tubers medium to large, round-flattened to heart-shaped, 
flattened, usually broader at the stem end ; pinkish tinge about the 
eyes, especially when freshly dug; skin dull white or light russet, 
usually roughened or cracked ; flesh solid and quite heavy. 

Rural New Yorker No. 2. — Originated by E. S. Carman. Intro- 
duced into trade about 1S89. Season medium late. Vines thrifty 
and strong. Tubers oblong, inclined to round or round-oval, rather 
flattened ; eyes few, shallow ; skin pure white netted ; flesh white. 

Sir Walter Raleigh. — Originated by E. S. Carman. Claimed to 
be a seedling of Rural New Yorker No. 2. Introduced into trade 
in 1897. Vines similar in habit and color of flowers to those of 
Rural New Yorker, No. 2, but color of stems not as pronounced. 
Color of flesh and skin of tubers is the same;' quality better than 
that of Rural New Yorker No. 2. 



REFERENCES 

Baker. A Review of Tuber-bearing Species of Solanum. Linn. 

Soc. Journal Bot., 20 : pp. 489-507, pis. 
Fitch, C. L. 

Identification of Potato Varieties. Iowa Extension Bui. 20. 1914. 
Kohler, A. R. 

Potato Experiments and Studies at University Farm in 1909. 
University of Minnesota Bui. 118. April, 1910. 
Mtlward, J. G. 

Commercial Varieties of Potatoes for Wisconsin. University of 
Wisconsin Bui. 225. July, 1912. 
Percival, John. Agricultural Botany, pp. 439—451. 
Stuart, Wm. 

Group Classification and Varietal Descriptions of Some American 
Potatoes. U. S. D. A. Bui. 176. March 27th, 1915. 



CHAPTER IV 
POTATO BREEDING 

The cultivated potato of to-day has undergone a re- 
markable change since its first introduction into Europe 
by the Spaniards. Some of this change has been brought 
about by better cultivation, but most of it is due to breed- 
ing. The tubers of the wild S. tuberosum were small 
and attracted little attention. Heriot, in his report on 
Virginia, describes the plant "with roots as large as a 
walnut and others much larger ; they grow in damp soil, 
many hanging together as if tied on ropes." The potato 
as we know it has been developed by means of conscious 
and unconscious selection and by hybridization with 
other species. The modern potato has not only been 
much changed by breeding, but it is now grown in widely 
different surroundings which produce various changes 
in the tubers. 

There are three foundations on which the increased 
productivity of crops rests — the enrichment of the land ; 
its tillage and care ; and the production of better varie- 
ties and strains. The first two are concerned with the 
environment of the crop, such as cultivation, fertilization, 
freedom from insects, disease and so forth, and the last 
with its heredity. We have long given attention to 
environment; now we are studying heredity with new 
enthusiasm and purpose. One of the "signs of the 

47 



48 The Potato 

times" is the attention that is being given to the practi- 
cal breeding of crops. We have learned that good seed 
is a necessary accompaniment to high fertility and good 
care and also the desirability of different varieties adapted 
to varying needs of soil, climate and man. 

These wild forms have been taken, in most cases, from 
their original habitats and placed under conditions of 
soil, temperature and moisture to which they are not 
accustomed. Here selection must not only modify the 
plants better to meet the wants of man, but they must 
become adapted to their new environment. Most 
plants are very flexible and finally become adapted to a 
variety of conditions. This is evidenced by the very 
large number of varieties of which most of our cultivated 
plants consist. 

Results of careful and systematic breeding are accu- 
mulating rapidly with very many kinds of plants. The 
results of all this work will probably enable us, even- 
tually, to formulate somewhat definite statements as to 
how to proceed to secure desired results. Considerable 
evidence is already at hand, but on the whole the methods 
of breeding are still somewhat empirical. 

All of our cultivated plants have come from wild forms. 
Man has seen in them possibilities of usefulness, and he 
has chosen year after year the ones which better serve 
his purpose. This constant selection has in the course of 
time produced profound changes in our plants. 

IDEALS FOR THE POTATO CROP 

Plant-breeding is worthy of the name only as it sets 
definite ideals and is able to attain them. Merely to 
produce new varieties is of no merit. We must give up 



Potato Breeding 49 

the production of mere novelties unless the new variety 
possesses some property which makes a real contribution 
to our present varieties. 

It is unfair and dishonest consciously to rename old 
varieties under the pretense of producing something new. 
Our list of varieties contains many synonyms, and these 
should not be consciously increased. 

In general, the improvement of our present standard 
varieties offers greater opportunities for the increased 
efficiency of the new generation of plants than the pro- 
duction of entirely new varieties. 

Ideals for the perfect potato will change in the different 
localities. Certain attributes, however, are universally 
desired. These are as follows : 

(1) High yield. 

(2) Good quality. 

(3) Disease-resisting capabilities. 

(4) Good keeping qualities. 

(5) Good color of flesh and skin. 

(6) Skin of desirable texture. 

(7) Tubers of good shape. 

(8) Shallow eyes, relatively few in number. 

(9) Maturing in season common to the variety. 

(10) Upright, vigorous plants. 

(11) Heavy leaf cuticle. 

(12) No tendency to make second growth. 

(13) Trueness to type of variety grown. 

High yield is essential if the grower expects to continue 
raising potatoes for market. In aiming to secure high 
yield, however, we should remember that there are many 
other factors which determine the marketability and 
price of the product. Tubers of inferior quality, size 



50 The Potato 

and the like are not of great value even in large quan- 
tities. 

From the consumer's point of view, quality is highly 
important. The grower would do well to keep his pota- 
toes up to standard in this respect. Potatoes intended 
for human consumption should have a mealy flesh when 
boiled or baked. Up to a certain limit the quality 
improves with an increase in starch content. Potatoes 
to be used for the production of alcohol need be of no 
particular quality from the culinary standpoint. 

There are no disease-proof varieties, but some are 
more resistant than others. Resistance is more impor- 
tant in the East than in the Mississippi Valley. 

It is necessary to store potatoes for a long period, to 
supply the demands between crops. If the keeping 
qualities of a strain are poor, there are fewer potatoes 
which can be sold in the spring. In a sense, then, poor 
keeping quality is a factor which decreases yield. 

The ideal color of skin and flesh will depend largely 
upon market preferences. In general a yellow skin and 
white flesh are desired. In the South, the red- or pink- 
skinned varieties are in favor. Because of the red color 
of some weak varieties, growers are likely to be skeptical 
of all colored varieties. 

The skin may be thick, medium, or thin. When grown 
in sandy soil, the skin is usually smoother than when 
grown in heavy loams. A netted and slightly rough skin 
is preferred, many believing that it indicates proper 
maturity and good quality. 

Flat-round or flat-oval tubers are better than the spher- 
ical, as the cortical and outer medullary layers, containing 
the starch, are relatively larger. Also a flat tuber bakes 
better, because the center is not too far from the outside. 



Potato Breeding 51 

Deep eyes cause waste in peeling. They hold mois- 
ture, thereby causing decay in storage. The tuber 
should have enough eyes to make good seed, but not so 
many as to make peeling difficult. 

Early varieties may mature in 70 to 90 days after 
planting; second-earlier in 90 to 130 days; and late 
varieties may continue to grow for 200 days. It is im- 
portant to choose a variety adapted to the locality. 

The haulm and leaf are considered more important 
than formerly. Large haulms require wider spacing of 
plants and greater expense for spraying. Short-haulmed, 
upright, heavy-leafed tops are not as susceptible to dis- 
ease as the prostrate types. The upright types are more 
likely to suffer during very dry spells, however, because 
the tops do not prevent the evaporation of moisture from 
the soil as do those of the more prone types. Care should 
be exercised to select a variety which is well suited to 
local conditions and which will grow vigorously. Dif- 
ferences in vigor will be noted in different strains of the 
same variety. 

Leaves with thick cuticles are not as easily penetrated 
by disease spores. 

When a period of drought is followed by a wet spell, 
second growth is likely to begin. The dry weather 
checks growth and the tubers begin to mature. Subse- 
quent wet weather restarts growth. Such abnormalities 
should be discarded in selecting seed. 

It is essential that the seed be as represented. None 
but experts can tell the different varieties apart, so seed 
should be obtained from a reliable source. 

The half-tone illustrations in Plates III to VII show 
some of the desirable potato forms, and also results in 
breeding. 



52 The Potato 

Use of score-card 

A score-card presents in a logically arranged, tabular 
form the different factors which make up an ideal potato. 
These factors are given relative importance or weight by 
means of percentage numbers, the sum of which is 100. 
One should make frequent use of a score card to familiar- 
ize himself with all details and to compare his product 
with the theoretical ideal product, which it describes. 

The score-card should be studied so as to establish the 
ideal of the desired variety firmly in mind before any 
attempt is made at improvement. 

When breeding a crop, special attention should be paid 
to the details. The proper combination of the little and 
usually overlooked points makes the perfect crop. 

It is important, further, to bear in mind the fact that 
a variety which is merely as good as any other in culti- 
vation is not worth introducing. It should be better in 
some particular than any other in existence. The oper- 
ator must know the points of his plant, as an expert stock- 
breeder knows the points of an animal, and he must 
possess the rare judgment to determine which charac- 
ters are most likely to reappear in the offspring. Inas- 
much as a person can be an expert in only a few plants, 
it follows that he cannot expect satisfactory results in 
breeding any species which may chance to come before 
him. Persistent and uniform effort, continued over a 
series of years, is generally demanded for the production 
of really valuable varieties. Thus it often happens that 
one man excels all competitors in breeding a particular 
class of plants. If the operator — himself an expert 
judge of the plant with which he deals — chooses his 
seeds with care and discrimination, and then proposes, 




> 



* 





Plate V. — Typical early and late potatoes. Top, Irish Cobbler (early). 
Bottom, Rural New Yorker Gate) . 



Potato Breeding 



53 



if need be, to follow up his work generation after genera- 
tion by means of selection, the work becomes plant- 
breeding of the highest type. 

First of all, therefore, the operator must know what he 
is likely to secure, and what will probably be worth se- 
curing. Most persons, however, begin at the other end of 
the problem, — they get what they can, and then let the 
public judge whether the effort has been worth the while. 

The following score-card has been adopted by the 
New York State Potato Association : 



Potato Score-card 





Conformity to 

Vaiubtal Type 

100 Points 


CONFOItMlTY TO 

Mabkmt Demand 

100 POINTH 




Perfect 


Perfect 


Flemishes and disease . . . 

Ihape 

Size 

Quality of flesh 

Depth and frequency of eyes . 
Color and texture of skin . . 


20 

15 
15 
10 
10 
15 
15 


20 
20 

15 
15 
10 
10 
10 




100 


100 



This score-card is arranged with the idea of empha- 
sizing the more important characteristics to be con- 
sidered in selecting potatoes both true to varietal type 
and in accordance with market demands. These two 
sets of qualifications are in many cases quite distinct. It 
is, therefore, true that the variety which fulfills both of 
these requirements is the one that scores highest and of 
which production should be encouraged. 



54 The Potato 

Uniformity. — Exhibit should be uniform in all phys- 
ical characteristics. 

Blemishes and disease. — ■ Should be no evidence of 
blight, rot, grubs, rhizoctonia, sunburn, or injury from 
rough handling. 

Shape. — Should be typical of the variety. Market 
demands a moderately oval-flat or round-flat shape. 

Size. — Should be typical of the variety. Market 
demands a medium-sized potato. 

Quality of flesh. — Should be true of the variety. 
Market requires a fine-textured flesh of light color, free 
from excess moisture and from hollow or dark spots. 

Depth and frequency of eyes. — Should be typical of the 
variety. Market demands few and shallow eyes. 

Color and texture of skin. — Should be typical of the 
variety. Market demands a thin, smooth skin. White- 
skinned varieties are preferable in most markets. 

POSSIBILITIES OF IMPROVING THE POTATO 

Even though the potato has been in cultivation for 
centuries, further improvement is by no means impos- 
sible. It responds very quickly to breeding. Most 
varieties are very impure and contain various types. 
The first task of the breeder is to become thoroughly 
acquainted with his plants so as to discard the poor 
plants and save the good ones for future planting. If 
this is done for a few years, the average yield of the 
crop and its uniformity will be greatly benefited. 

The hill selection of potatoes is not generally practiced 
and as a consequence the varieties soon deteriorate and run 
out. This deterioration could be easily prevented by pay- 
ing careful attention to planting seed from the best hills. 



Potato Breeding 55 

It must not be forgotten that potatoes are now grown 
in regions where the climate is not entirely congenial 
to them. This constant action of a somewhat unfavor- 
able climate will also cause them to degenerate if not 
counteracted by seed selection. 

Careful experiments have been conducted with pota- 
toes in which the offspring of different tubers are planted 
and recorded separately. Many of these progenies seem 
to degenerate completely, indicating that some degen- 
erative factor, still unknown, is constantly at work. 
This deterioration is partially due to disease, without 
doubt, but some of it also is of a physiological nature. 

The yields of any field or the average yields of any 
locality or of an entire state are far below what they 
should be. This is due to two causes : the conditions 
surrounding the crop have not been the best — perhaps 
insufficient food supply or water or poor soil; and sec- 
ondly, the absence of seed selection has produced a poor 
stand of plants, many of which probably give low yields. 
By proper attention to fertilization, spraying and seed 
selection, the yield may often be doubled or trebled. 
Perhaps we can never expect the high yields to the acre 
obtained in Europe because of our hot dry climate 
(see Chapter I). 

If seed selection becomes generally practiced, with 
its accompanying increase in yields, vast consequences 
may be looked for. If all of the hills on an acre of pota- 
toes planted in the ordinary manner weigh one-half a 
pound, there will be a yield of 78 bushels to the acre. 
A half-pound hill, however, is very small. One ordinary- 
sized tuber will weigh more than that. If, by means of 
breeding, the average yield to a hill is increased to one, 
two or three pounds, which is not at all impossible, the 



56 



The Potato 



yields to the acre will be increased to 156, 312 and 468 
bushels respectively. If this reasoning were applied to 
all of the potato fields in the United States, the result 
would be almost unbelievable. Burbank has made the 
conservative estimate that if one tuber were added to each 
hill, the total resulting increase in the United States 
would be 21,000,000 bushels yearly. 

The following table gives the yields to the acre from 
hills of certain weights. It is assumed that the hills 
were 18 inches apart in the rows and the latter were 3 feet 
apart. This rate of planting gives 9372 hills on an acre : 

Table IX 



Yield to the Hill 


Perfect Stand 


90 Per Cent Stand 


Pounds 


Bushels to the Acre 


Bushels to the Acre 


.5 


78.1 


70.29 


1.0 


156.2 


140.58 


1.5 


234.3 


210.87 


2.0 


312.4 


281.16 


2.5 


390.5 


351.45 


3.0 


468.6 


421.74 


3.5 


546.7 


492.03 


4.0 


624.8 


562.32 



METHODS OF IMPROVEMENT 

Plants are improved in three ways : first, by simple 
selection, that is, breeding from the best, the object 
being to improve the present varieties rather than the 
production of new ones; second, to conduct extensive 
plantings for the purpose of discovering some unusually 
good individuals or mutants, which may become the 
foundation of improved varieties and which subsequently 




Plate VI. — Breeding — Each group of four plates represents the 
progeny of a tuber ; and each plate is the produce of a single hill. 



Potato Breeding 57 

require little else of the grower than their multiplication ; 
and third, by crossing plants to combine the best qualities 
of two or more parents in a new and improved variety. 

Improvement of the potato by selection 

The principal method of improving the potato is by 
bud-selection. Potato hills are very variable, and im- 
provement is made by planting tubers from the best 
hills. Many of these apparent improvements may be 
due to some advantage in growth, such as increased fer- 
tility, more light or moisture and so forth. Of course, 
this increase is only transitory, and not being inherited, 
produces no permanent advancement. 

The potato, however, presents variations which are 
inherited. These are of two kinds, — smaller differences 
whose inheritance produces a gradual change, and large dif- 
ferences or so-called "bud-sports" or bud-mutants which 
immediately become the starting point of new varieties. 

Potatoes differ from most farm crops in their manner 
of reproduction. They are propagated vegetatively 
without the intervention of a sexual process like corn 
or wheat. Each hill of potatoes comes from one tuber or 
a part of a tuber which was the product of one bud of the 
mother plant. Hence the entire hill becomes a unit, and 
hill selection is, in reality, bud-selection. Single tubers 
cannot be said to be units from the breeder's standpoint. 
Therefore, it is of supreme importance to take into ac- 
count the yield of an entire hill and not the presence in 
it of two or three large tubers resulting in low total yield 
for the hill. 

So far as man is concerned, the origin of the initial 
variation is largely chance, but this start or variation 



58 The Potato 

once given, he has the power, in most cases, to perpetuate 
it and to modify its characters. There are two very 
different factors or problems in the origination of potato 
varieties by selection, — the production of the first de- 
parture or variation, and the subsequent breeding of it. 

It is apparent that the very first effort on the part of 
the potato-breeder must be to secure individual differ- 
ences. If the plants which he grows are very much alike, 
there will be very little hope of obtaining new varieties. 
He should, if possible, cause his plants to vary. This 
initial variation may usually be induced by changing the 
conditions in which the plant has habitually grown, as 
a change of seed, change of soil, tillage, varying the food 
supply, crossing and the like. As a matter of fact, how- 
ever, nearly all plants which have been long cultivated, 
like the potato, are already sufficiently variable to afford 
a starting point for breeding. The grower should have 
a vivid mental picture of the variety which he desires to 
obtain ; then he should choose those hills which most 
nearly meet that ideal. 

Experimental breeding has demonstrated that the 
different varieties of farm and garden plants, as we ordi- 
narily know them, are not entirely homogeneous and 
uniform, but are made up of smaller groups now known 
as "pure lines." It is ordinarily understood that a pure 
line is the progeny of a self-fertilized individual, that is, 
one in which all effects of crossing have been eliminated 
by constant self-fertilization. In potatoes which are 
ordinarily propagated asexually, a pure tuber line would 
be the progeny of a single tuber. 

Experiments seem to demonstrate that the group of 
individuals known as a pure line vary much less than the 
variety as a whole, and that selection of the best indi- 



Potato Breeding 59 

viduals within a pure line has little, if any, effect in raising 
the average of the line. This has not been proved, by any 
means, but the indications are that only a very slight ad- 
vance is made by continued selection after a pure line has 
been reached, unless an exceptionally good individual 
should arise whose progeny would constitute a new and 
better line. 

It will now be seen that the first work in improving 
potatoes by selection is to determine the best tuber lines 
and plant them for seed. This necessitates carrying out 
a system of breeding whereby individual tubers must 
be planted separately and properly labeled and their prog- 
eny kept separate for a few years to determine whether 
or not the desirable plants transmit their qualities to fu- 
ture generations (see Plate VI). This is known as "pedi- 
gree breeding." Myers gives the following table to show 
variation in the yielding capacity of different tubers. 
Each unit is the product of a different parental tuber : 

Table X 

Unit Yield in Bushels 

No. to the Acbe 

1 110 

2 220 

3 220 

4 230 

5 280 

6 320 

7 240 

8 230 

9 230 

10 130 

11 210 

12 70 

13 190 

14 ... 190 

15 25 

16 . ■ 270 



00 



The Potato 



If the first work of breeding consists of separating out 
pure lines and if there is very slow progress within these 
lines, it is obvious that the choice of individuals for 
planting the first few years is all-important. As large 
fields as possible should be grown to give opportunity 
for all of the best plants to appear. 




Number 
diseased 
tubers 
to row 



Fig. 8. Potato yields. Diagrams showing variation in yield of in- 
dividual rows of potatoes grown on special seed plots in 1909. (Carman 
No. 1, by R. H. Crosby, Markham, Ont.) 



Until recently, the method of selection has been to 
choose from the potato bins in the spring the requisite 
amount of seed, using tubers having the desired size and 
shape but without knowledge of whether they came from 
high yielding strains or not. This method of choosing 
seed from year to year, using merely the best tubers 



■ 





munity and susceptibility of two tuber progenies. 



Potato Breeding 



61 



without a knowledge of their ancestry or obtaining a 
test of their producing power, is known as "mass-selec- 
tion." This method will inevitably lead to improvement 



/ Z 3 * J 6 7 Q 9 /0 „ * 0»,5 /6 ,7 /8 ^°^Z3 2 ^S 



/J20 

//O 

/oo 

90 
80 
70 
60 
50 
40 
30 
20 
/O 
O 



^""h::^ 



Fig. 9. Continuation of Fig. 8. 



because the very poor hills will not produce good tubers, 
and hence will be eliminated. But the improvement is a 
very slow one. In employing this method of mass selec- 



62 The Potato 

tion, growers were working blindly without knowing how 
or when or even whether they were going to reach a sta- 
bility of type. On the other hand the method of pedi- 
greed culture or "individual selection" eliminated the 
fear of failure because of the appearance of the hitherto 
unsurmountable variations. 

Plants which have any desired characteristics in com- 
mon may differ widely in their ability to transmit these 
characters. It is generally impossible for the cultivator 
to determine, from the appearance of any given progeny, 
the most invariable and the most like its parent ; but it 
may be said those individuals which grow up in the most 
usual or normal environments are most likely to perpet- 
uate themselves. A very unusual condition, as of soil, 
moisture or exposure, is not easily imitated when provid- 
ing for the succeeding generation, and a return to normal 
conditions of environment may be expected to be followed 
by a more or less complete return to normal attributes 
on the part of the plant. If the same variation, therefore, 
were to occur in plants growing under widely different 
conditions, the operator who wishes to preserve the new 
form should take particular care to select his tubers from 
those individuals which seem to have been least influenced 
by the immediate conditions in which they were grown. 

The method of individual selection or pedigree breed- 
ing is now universally accepted by the best breeders. 
In potato-breeding it is known as the "tuber-unit" 
method, that is, the progenies of individual tubers are 
tested for a number of years to determine the best pure 
lines which are constant from year to year. 

One of the first and best methods of breeding potatoes 
by the tuber-unit or pedigree plan has been devised by 
H. J. Webber. This method is so satisfactory, when 
properly carried out, that it is given here in detail : 



Potato Breeding 63 

Selection of foundation stock of potatoes. — Probably no crop 
generally grown is more influenced by environment than the potato. 
The experience of growers indicates that a variety found to be the 
best suited to local conditions on one farm may not prove to be the 
variety best suited to the conditions existing on an adjoining farm. 
It thus becomes desirable for any farmer who is growing potatoes 
extensively to test varieties sufficiently to determine which is the 
variety best suited to the local conditions concerned. This ordi- 
narily does not require an extensive test as the experience of growers 
in a region has usually shown the general superiority of a com- 
paratively few varieties, and a test can thus be limited to these varie- 
ties which in general are known to be the best. The writer would 
not urge tlus test of varieties, if it were not very important to begin 
any breeding work with the best variety available. Breeding work 
requires so much attention that it does not pay to start with an in- 
ferior variety. The first effort of any one contemplating breeding 
with potatoes is thus to determine the best foundation stock to use 
for the selection work. If the grower has had extensive experience 
in growing potatoes and has determined that a certain variety 
gives the best results under his conditions, he is in a position to start 
the selection without a further test of varieties. 

Growing potatoes for selection. — The influence of the number of 
eyes and size of piece planted as seed has so much to do with the 
yield of the hill that fields planted in the ordinary way are very 
poorly adapted to begin the work of selection. It is of primary im- 
portance that the first selections be of the very highest type obtain- 
able, as it is a common experience that the first selection is the most 
important. Too much attention cannot be given therefore to the 
first selection. The writer would thus urge the following method 
as one of the most satisfactory to be pursued : 

(1) Examine a large number of tubers of the variety selected as 
the foundation stock and decide on the most desirable shape and 
type of tuber. In general a moderately large tuber, which is oblong 
or somewhat cylindrical in shape and oblong in cross section, is 
considered most desirable. A spherical tuber if sufficiently large 
to be desirable is so thick that in cooking the outside is likely to 
become overdone before the interior is properly cooked. A tuber 
with shallow eyes, netted surface and white color is also usually 
preferred. Probably the best-sized potato for general use is one 
weighing seven to eight ounces. A potato of this size does not have 



64 The Potato 

to be cut when served, as a single tuber is about the right size to an 
individual. Again this sized tuber is well fitted for cooking and it is 
small enough so that the interior will cook nearly as quickly as the 
exterior. Probably the most desirable shape is when the tuber has 
a major axis or length of three and one-half inches to four inches, with 
a width of possibly three to three and one-fourth inches, and a thick- 
ness of two to two and one-fourth inches. In a tuber of this shape 
the center of the potato at any point is only about one inch from the 
exterior. 

(2) When the ideal character and size have been determined, 
examine a large number of tubers and pick out a thousand or more 
having this size, shape and general character. This is work that 
can be done in the late fall and winter when there is no rush of other 
farm work, and time should be taken to secure a considerable number 
of these tubers of the same character. These are to be used for 
planting the selection plot, and the number selected should correspond 
to the size of the plot which it is desired to plant, four hills being 
planted with each tuber. There should certainly not be less than one 
thousand, and a much larger number is more desirable. The pro- 
spective breeder should remember that success in breeding work de- 
pends upon selecting the one individual that gives the very highest 
yield possible under the conditions, and the larger the number of 
individuals examined the more likely is he to discover the one produc- 
ing the maximum yield which will give a valuable new strain. There 
is no loss in growing this selection plot aside from the greater amount 
of time required for the digging, so that one should grow a consider- 
able number of plants. 

(3) The planting should be arranged in such a way as to secure 
a test of the productivity of each tuber. To do this the following 
method may be recommended. Cut each tuber into four uniform 
sized pieces, making each cut longitudinally so that each piece 
will contain an equal proportion of the basal end and the apical end 
of the tuber. Plant four hills with each tuber, one piece in the hill. 
These should be planted consecutively in each row beginning at one 
end, so that starting at that end the first four hills will be from one 
tuber, the second four from another and so on throughout the 
length of the row. The object in planting this way is that four hills 
can be dug together and the total product weighed to obtain a meas- 
ure of the productivity of the seed tuber planted. Probably the 
best way to plant these is to drop the selected tubers one to each 



Potato Breeding 65 

four hills and then go over the row and cut each tuber and plant 
its quota of four hills. The hills in the row should be planted some- 
what farther apart than in ordinary planting, probably 20 to 24 
inches. If this is not done, a somewhat greater distance than ordinary 
should be left between each two four-hill tuber-units. The writer 
would advise that one hill be left unplanted between each two four- 
hill units. It would doubtless be convenient and desirable to have 
the plants in rows both ways to facilitate digging. For this selec- 
tion-plot of potatoes, choose a field of moderately good fertility and 
as uniform throughout in soil as it is possible to obtain. 

(4) Manure and cultivate the plot of potatoes grown for selec- 
tion just the same as you do your ordinary crop. 

How to make the selection of potatoes — field examination. — A 
careful examination of the selection field should be made as the 
vines begin to mature and while they are yet green. This examina- 
tion should include observations on diseases and vigor of the tops. 
If there are any marked differences apparent between the different 
four-hill units, those with the best-appearing, most healthy tops 
should be marked by small stakes which can be stuck in the ground 
beside the hills. This field examination, while important in careful 
work, probably could be omitted without very great loss, as after all 
the yield is the primary character. 

Digging the selection field. — The digging of the field grown for 
selection purposes requires considerable care, and here hard work is 
necessary. Dig each four-hill unit grown from the same tuber sepa- 
rately, being careful to get all of the product, and avoid cutting or 
injuring the tubers if possible. Carefully place the product of each 
four-hill tuber-unit together at one side of the row, and if it is a tuber- 
unit marked with a stake in the field examination, keep the stake 
with the product of the unit. A good way to dig in order to avoid 
getting the hills of different tuber-units mixed is to dig across the 
field, in a direction at right angles to the direction the rows were 
planted. First dig the four hills of the first tuber planted in the first 
row, then the four from the first tuber in the second row, then the 
same in the third row, fourth row, etc., through the field. Next 
dig the four hills from the second tuber planted in the first row, then 
the four from the second tuber in the second row, etc. By this 
method of digging, especially if the hills are rowed both ways, there 
will be little danger of mixing the product of the four-hill units. 

Making the selections. — The problem after digging is to select 



66 The Potato 

fifty to one hundred of the best tuber-units, — best, that is, in yield, 
uniformity of product, color, shape, etc. After the potatoes are dug 
and the product of each tuber-unit is laid out separately, the real 
work of selection begins. The following are the important steps in 
this process : 

(1) Go over the field and study the tuber-units in a gross way 
until you have well in mind the variations in yield and the gen- 
eral uniformity of the tubers in the various tuber-units. Re- 
member that the total yield is not the only important character. 
What one wants is to discover those tuber-units which have the 
largest yield of good merchantable potatoes of the best shape and 
appearance. Size up the field as a whole with reference to these 
characters. 

(2) Go over each row carefully and throw out all of those tuber- 
units which can be clearly seen to be inferior ; these may be thrown 
together and placed with the general crop of potatoes. For the 
interest of the grower, however, it would be well to weigh the prod- 
uct from some of the light-yielding tuber-units and preserve the 
figures for the sake of showing the extent of variations occurring. 
By this first discarding process the number of tuber-units will proba- 
bly have been reduced to two or three hundred. It is very prob- 
able that in some cases one or more of the hills of a four-hill tuber- 
unit will not grow. In such cases the tuber-unit will have to be 
judged in proportion to the number of hills actually grown. 

(3) Now provide yourself with scales of some handy pattern 
like the ordinary counter scales used by grocers, with which the 
product of each tuber-unit can be easily and quickly weighed. A 
satisfactory scale should weigh accurately to at least a half ounce. 
Weigh the product of the remaining tuber-units, examine the tubers 
more carefully as to their character and uniformity of size in the 
tuber-unit and select about fifty of the best units. These fifty 
units should naturally be from those marked as having good healthy 
vines in the first examination before digging, unless all of the vines 
at that time were in fairly good condition. In making these final 
selections, if some hills in the tuber-unit are missing, the comparative 
yield can be easily calculated. If one hill is missing, a comparative 
yield for four hills is obtained by increasing the weight from the three 
hills by one-third. If two hills are missing, a comparative yield for 
four hills would be double that obtained from the two hills. If more 
than two hills are missing, discard the unit entirely. 



Potato Breeding 67 

The product of the tuber-units selected should then be placed in 
paper bags, the product of one tuber-unit only being placed in a bag. 
A good bag for the purpose is the 12 or 16 pound manila paper bag 
used by grocers. The 12-pound paper bags of good quality should 
cost only about 40 cents per hundred. If the 12-pound paper bag 
is too small, use a 16-pound bag. In your notebook record under 
the number of each tuber-unit, the number of large, medium-sized, 
and small tubers and the total weight of the product. The bags 
containing the seed should then be placed in suitable storage where 
they will not be torn or the tubers mixed. The tubers from the 
best discarded tuber-units should be retained to plant the general 
crop the next year. 

If at digging time the grower is crowded with work and wishes 
to save time, the two or three hundred tuber-units retained after the 
first gross selection (see paragraph 2 above) could be placed in paper 
bags and the more careful examination and weighing of the product 
delayed until some convenient time during the winter when the final 
selection could be made. 

Selecting seed for the second years planting. — Some time during 
the winter or at any convenient period before planting time care- 
fully examine the product of each select tuber-unit and pick out the 
ten best tubers of each as judged by the ideal standard of a good tuber 
which has been taken as the type of the selection. The ten best of 
each retain in the numbered sacks for planting and discard the re- 
maining tubers. 

Second year's planting. — In the further handling of the selec- 
tions made the first year the planting the second year must be ar- 
ranged in order to test the productive power of each of the fifty 
select tuber-units. Plant each tuber-unit in a row by itself by the 
same method used in planting the first year's crop (see p. 64). That 
is, plant four hills with each tuber, cutting the tuber longitudinally 
into four equal-sized quarters, making each cut from base to apex 
of the tuber. As ten select tubers were retained from each tuber- 
unit this will make forty hills per row, and if fifty tuber-units were 
selected, there will be 500 tubers to plant, which will make a total 
of 2000 hills in the breeding-plot. The land used for this breeding- 
plot should be carefully chosen for uniformity, as variations in the 
land will modify the comparative yield and are likely to render the 
results untrustworthy. Number each row of forty hills with the 
number given the tuber-unit of the preceding year. It is desirable 



68 The Potato 

for comparison to plant about every tenth row with unselected 
seed of the same variety, cut and planted in the same way, but 
without reference to keeping each tuber separate. The production 
of these check-rows will show whether progress is being made in the 
selection. 

Cultivate the breeding plot and treat it otherwise just as an ordi- 
nary crop is treated. 

Making the second years selection. — When the breeding plot 
ncars maturity, the individuals should be examined and either the 
best and healthiest vines marked or, if easier, the diseased vines 
showing weakness marked, so that they can be discarded later. 
Then dig each tuber-unit as in the preceding year, placing the tubers 
from each four-hills together at the side of the row. Each unit should 
then be weighed and the number of large, medium and small sized 
tubers recorded. This will enable the breeder to determine which of 
the original fifty tuber-units selected in the first year has given the 
largest average yield in the ten tuber-units or forty-hill test, and 
this is the primary test of the value of the original selection. Follow- 
ing the same method as used the first year, select from the breeding- 
plot the fifty best tuber-units, and preserve the tubers of each unit 
separately in a paper bag. The majority of the selection in this 
year should naturally be made from those rows which have given 
the highest yield. Number the tuber-units selected in this second 
generation 1-1, 1-2, 1-3, etc., and 2-1, 2-2, etc. In such hyphenated 
numbers the first figure refers to the number of the tuber-unit se- 
lected the first year, and the second number, that following the 
hyphen, refers to the number of tuber-units elected from this prog- 
eny the second year. Thus in the case of 2-2, the first 2 indicates 
that it was the second tuber-unit selected in the second year from 
progeny of unit No. 2 of the first year's crop. In the third year the 
numbers can be extended by the same principle, the tuber-units 
selected from progeny 2-2 in the third year being numbered 2-2-1, 
2-2-2, 2-2-3, etc. These numbers can be placed on the bags and 
notes on weight of yield, number of tubers per unit, etc., recorded 
under the same number. 

All of the good tubers from the remaining tuber-units of the 
breeding-plot not selected should be retained for planting a multi- 
plication-plot the third year, which should furnish sufficient seed for 
planting the general crop for the fourth year. 

At some convenient period before planting time, as in the pre- 



Potato Breeding 69 

ceding year, go over the product of each select tuber-unit and pick 
out the ten best tubers of each for the next year's planting. 

Continuing selections in third year. — In the third year, the fifty 
selections of heavy yielding tuber-units should be planted by the 
same method used the second year, at least forty hills of each selec- 
tion being planted. The row from each unit should be plainly la- 
beled or otherwise marked to avoid mixing the pedigree. Treat this 
breeding-plot as described for the breeding-plot in the second year, 
weigh up the product of each four-hill tuber-unit in the same way to 
determine which unit of the second year's selection has transmitted 
in greatest degree the tendency to yield heavily. Finally, select 
again the best fifty tuber-units to continue the breeding, and retain 
the good tubers of discarded units to plant a multiplication in the 
fourth year. 

In the third year, a multiplication-plot should be planted with the 
good tubers from the discarded tuber-units of the breeding plot of 
the second year. In planting this plot the grower can use any 
method of cutting and planting the tubers which he thinks most 
desirable. This plot should give enough seed to plant a fairly large 
plot in the fourth year. 

Continuing selections in fourth and succeeding years. — In the 
fourth and succeeding years the selection should be conducted by 
the same plan as outlined above. When this system is well under 
way, it will be seen that each year the breeder is growing a small 
breeding-plot, a large multiplication-plot for seed and a general 
crop. 

Further considerations. — As the selection progresses many of the 
strains from the original fifty tuber-units will be entirely discarded. 
The breeder must be continually watching for the appearance of a 
hqavy yielding strain, and if such a strain is discovered, all of the 
further selections should be made from this strain. 

In advocating the selection of but fifty tuber-units and the 
planting of ten tubers only from each select unit the writer has 
had in mind the reduction of the work to a comparatively simple 
plan which would be better to handle larger numbers if the grower 
is so situated that he can take the time for it. It is, however, better 
to use comparatively small numbers carefully than to attempt to 
handle large numbers and find the work too extensive. 



70 The Potato 

Another method of selection has been suggested which 
is simpler than Webber's method, probably not as satis- 
factory, but which has been found very useful by many 
growers. It consists of planting, growing and digging 
the tubers the first year as previously suggested, but in- 
stead of weighing the hills and keeping them separate for 
further tests, they are chosen by means of counting in- 
stead of weighing. If the season has been an average 
one, the hills which have six or more good tubers are 
saved for future planting. Perhaps it may be necessary 
to use five as a standard of selection or even seven may be 
used if the crop is good. There is no attempt at pedi- 
gree breeding by keeping the different strains separate. 
All hills meeting the established standard are thrown 
together and saved for seed. The next year these are 
planted and grown like the rest of the field. In the fall 
they are dug by hand and again the best hills by count 
are saved for seed. This method will gradually elimin- 
ate the poor strains and raise the average yield of the 
crop very rapidly. 

Spillman says: "A potato grower in Michigan some 
years ago began the practice of digging by hand enough 
potatoes for seed and saving only those hills that had six 
or more merchantable tubers and no small tubers. When 
he first began this practice, only sixteen hills out of each 
hundred dug came up to his standard, but after he had 
continued this practice for five years the number of such 
hills had risen to seventy in a hundred." 

Another similar instance is found in some unpublished 
results secured by Dodge of the office of Farm Man- 
agement, who for several years has been teaching some 
New England potato-growers how to select seed potatoes. 
The method adopted is to save for seed those hills that 



Potato Breeding 71 

produce six or more merchantable tubers. This experi- 
ment has extended over three years. The first year, 
from 7 per cent to 8 per cent of hills were found that met 
the requirements ; the second year from 17 per cent to 
20 per cent. This season the number of hills which have 
produced six or more merchantable tubers has risen to 
24 per cent to 27 per cent. 

Whenever pure lines or strains or varieties of potatoes 
are compared, every effort should be made to eliminate 
soil differences or other factors of environment, so that a 
direct test of the heredity only can be made. Potatoes 
are so easily influenced by environment that real heredi- 
tary differences are often covered up. Absolute uni- 
formity in time of planting, methods of culture, spraying 
and so forth are essential. The seed pieces should be as 
nearly the same weight as possible. Arthur says, " What- 
ever increases rate of growth at the beginning, increases 
yield." 

If tuber-units are being compared, they should be 
planted in duplicate or preferably in triplicate in differ- 
ent parts of the field and their production averaged. 

If single high-producing hills are saved for the next 
year's planting, one should make sure that they did not 
come from some highly fertilized part of the field. Pref- 
erably they should be chosen from the poorer parts of the 
field when their production may be high in spite of their 
environment, the real test of heredity. 

Zavitz, of the Ontario Experiment Station, selected 
the best hills of seven varieties of potatoes for a period 
of sixteen years. During the first four-year period 
the average yield was 120 bushels. During the three 
succeeding periods of four years each, as a result of 
selection, the average yields were increased to 216, 218 



72 



The Potato 



and 249 bushels. Within the sixteen-year period, the 
methods of culture were kept practically the same 
aud the result is, therefore, attributed to the result of 
selection. 

Waid has conducted at the Ohio Experiment Station 
a series of experiments for the purpose of securing data 
to throw more light on the question of the value of hill 
selection in potatoes. In this work, starting with the 
same original lot of tubers, three strains were grown 
as follows : (1) seed from high-yielding hills ; (2) seed 
from low-yielding hills; (3) unselected seed. The fol- 
lowing table gives the summary of the results that were 
obtained from high-yielding hills and from low-yielding 
hills: 

Table XI. — Summary of Results from Use of Seed Po- 
tatoes from High-yielding Hills and from Low-yield- 
ing Hills. (Variety, Carman No. 3) 



Source op Seed 


Yield of 100 Hills 


Number op Tubers in 
100 Hills 


Total 
1904 


Total 
1905 


Total 
1906 


Average 
1904-5-6 


Total 
1904 


Total 
1905 


Total 
1906 


Average 
1904-5-6 


High-yielding bills . 
Cheek rows . . . 
Low-yielding hills . 


Lbs. 

125 
115 

84 


Lbs. 

173 

136 

75 


Lbs. 

116 
79 
61 


Lbs. 

138 

110 

73 


781 
713 
566 


865 
630 
546 


676 
479 
364 


774 
607 
492 



Running out of varieties 

Potatoes are grown in many parts of the world where 
the climate and soil are very different from that of their 
native home. Also all of our varieties which have been 
developed as a result of breeding give yields far in excess 



Potato Breeding 73 

of the wild forms. The stress of uncongenial environment 
and large production of tubers causes most varieties to lose 
this abnormal (from the standpoint of the plant) produc- 
ing power and to decline unless selection is constantly 
practiced. Disease may be partially responsible for this 
degeneration. 

Running out of varieties is often caused by repeated 
planting of culls and poorer specimens while the best are 
sent to market. 

Newman x says, that in Sweden there is a potato known 
as the Dala, which is said to have been introduced about 
150 years ago and is still one of their best sorts. The 
opinion held at Svalof is that there is no period of old age 
in a variety of potatoes ; that where suitable sorts are 
used, and where suitable tubers of these sorts are used for 
seed purposes each year, the planting of the variety may 
be maintained indefinitely under all favorable conditions 
of soil and climate. The main considerations are mainte- 
nance of vigor and control of disease, and this implies 
careful selection of seed tubers, careful cultivation and 
spraying and rotation of crops. Special emphasis is 
laid upon the latter point. 

Orton says : " The same system of seed selection and 
treatment and crop rotation that will free the potato 
fields of wilt, leaf-roll, and curly-dwarf will at the same 
time not only bring under control the blackleg and some 
other diseases but will insure the maintenance of the 
strains cultivated in their most vigorous and productive 
condition and be free from objectionable mixtures with 
other varieties." 

The following statement from Fruwirth is representa- 

1 " Plant Breeding in Scandinavia." Canadian Seed Growers Associa- 
tion, Ottawa (1912). 



74 The Potato 

tive of the opinion held by most of the European experi- 
menters. "And the real degeneration, an ageing of a 
variety, which has been under uniformly favorable condi- 
tions and of which good seed is used has not been proved 
and is improbable." 

Varieties seem to differ in their staying qualities. 
Some have held up for 50 to 60 years, while others have 
passed out quickly. The old Peachblow variety which 
was widely grown forty years ago has largely run out 
now except in certain localities like the Carbondale region, 
where it has been given careful selection and is better 
to-day than ever before. 

Another reason ascribed is that long-continued bud 
propagation results in an inner physiological weakening. 
It is difficult to see, however, how prolonged asexual 
propagation affects stocks injuriously. 

What appears to be the running out of a variety may, 
in some instances, be due to a change in market demands 
and the varieties disappearing which do not meet these 
demands. For example, the old long Burbank has 
given place to the more round varieties such as the Rural, 
and the Blue Victor has been replaced by white varieties 
and has now practically gone out of existence. Fru- 
wirth believes that a lack of adaptation to local condi- 
tions results in a degeneration of certain varieties. Poor 
attention to the selection of seed tubers is also suggested 
as a cause of deterioration. Fruwirth summarizes the 
opinions of a number of German experimenters in sup- 
port of these two views. 

East points out that perhaps the potato requires 
frequent crossing to keep up the vigor, and that possibly 
continual propagation by asexual methods causes a loss 
of heterozygosis. 



Potato Breeding 75 

Certain plant characters are often associated together. 
In breeding practice a knowledge of these associations 
is often valuable. If easily observable physical char- 
acters, such as color of flower or texture of skin, are asso- 
ciated with, chemical composition, which is less easily 
detected, the appearance of the former is a valuable 
index to the existence of the latter. It has been often 
observed that there is a certain shade of green in the 
leaves which is correlated with vigor and high produc- 
tivity. If the leaves are too light green, few tubers will 
be produced, or if too dark, the yield is again small or a 
large number of small tubers will be found, due to late 
maturity or possibly to disease. Correlations are es- 
pecially valuable when they enable one to select out good 
plants in a young stage, or when they save the trouble of 
making elaborate chemical analysis. Only a few defi- 
nite correlations have been discovered in the potato. 
East reports nearly all of these in Illinois Bulletin 127. 

There appears to be a positive correlation between 
yield and the following : flat shape of tuber, number of 
stalks to the plant and length of the growing season. 
With a heavy setting of seed berries, we may usually 
expect a light production of tubers. No correlation has 
yet been found between color of the tuber and yield. 

Fischer of Germany (reported by East) says that round- 
flat tubers tend to produce plants which are rather com- 
pact in habit. Cylindrical tubers produce large, scraggly 
plants. 

Round-flat tubers are richest in starch. Quality is 
said to improve directly with an increase in starch con- 
tent up to a certain point. An excessive amount of 
starch causes the tuber to be coarse and woody. A 
netted skin is usually associated with high quality. 



re 

No correlation has been discovered between color of 
tubers and color in the stews and flowers, 

In certain varieties there seems to be a eouplui 
characters and what appears to be a close correls 

This same now hew ever, may not held for any 

ether variety b East points out, we ought to have .. 
good imderst.'. i of the lite history, of different varie 
ties before wo draw definite conclusions as to the eorrela- 
tien of characters, 

- 

Occasionally asin^lebud >up of buds, on a t x 

will give rise to • r dist . . j unlike any others of 
the variety is known as bud-sporting Just 

what causes this unusual be lavior we e* »eculate 

\o definite cause is known, 
N win reports three - • ■ oi bud sporting v -..--• oi 
the purple variety Fortj old das . / ej , n that v\ as 
white. This whe ve rise to .. white vj 

The same purple variety in another instance produc \ 

. . \- which bred true, The white variety Kemp" 
sported to give the red .'. \ o - Fort} fold/' 

Fruwirth repeats a ease where jrellow tuber 
rise to .. vioiet-skinned form. Examples . - sort 
are rax her numerous. 

Such bud spo is not lim ters of the 

tuber, Mam brieve that habit of vine, \%< produc- 
tiveness anol ox her characters may be affected by sporting 

. . . . .-.ids. 

;;\ carefully examining the bills oi i . eediixg plot 
g time, any valuable bud sports can be seleexed 
out for furth* 



Potato Breeding 77 

Trnprownient by hybfidi ation 

It is hardly advisable for the practical potato-grower 
(o attempt an extensive improvement of his crop by 
hybridization. While the method has yielded good 
results in some rases, there are maii\ difficulties in the 
way and the results are ven uncertain. The major 
portion of a farmer's potato breeding plot should he 
given over to tuber-unit tests. II' the grower Feels that 

he can spare the time and is willing to risk a failure in 
his enterprise, it would he <A interest and possibly i^ 
profit to attempt a few crosses between his better strain:;. 
Otherwise this method should he left lo the experiment 
station worker, who has the time to make the large 
number oi' manipulations necessary, and who can de\ole 

large areas to the growing o'i the seedlings. 

Plants are hybridized primarily to increase their \aria 
bility and to furnish more materia! on which to practice 
selection, In the light of modern mendelian studies, 
we have come to look upon hybrids as recombinations 
of characters present in the parents, Care should be 

exercised to choose parents having as many desirahle 
characters as possible. Subsequent selections should 

preserve those plants which combine the largest number 
of desirahle qualities from both parents. Hybridiza- 
tion Usually increases vigor and is often useful in restor- 
ing this characteristic in weakened strains. 

There are certain conditions which make the successful 
hybridization of potatoes very difficult. In the first 
place, there is a strong tendency in most varieties not to 
set seed, In such varieties, the flowers drop off shortly 

after pollination. This necessitates making a great 
many pollinations with the hope that a few plants will 



78 The Potato 

set seed. Salaman 1 estimates that only 5 per cent of 
his crosses set seed. East 2 found it difficult to get a 
good setting of seed in very dry seasons. 

In some cases, persistent attempts have finally resulted 
in a successful cross where at first it seemed impossible. 
A second drawback is the scarcity of pollen. Many 
varieties produce little or no pollen and have to be crossed 
if we are to get sexually produced seed from them. Also, 
some plants produce yellow pollen which is sterile and 
does not function. Other varieties rarely, if ever, flower. 

Most varieties of potatoes are already hybrid and 
when seed from them is sown, the type breaks up into 
many elementary forms, most of which are of no value 
to the grower. This adds another difficulty to those 
mentioned above. Each variety which is crossed trans- 
mits a number of undesirable, latent characters which 
come out in the hybrids. Often the seedlings from a 
cross will show so many of the traits of the wild potato 
that none of them is worthy of further attention. Se- 
curing a valuable new variety from a cross seems in this 
case to be largely a matter of chance. There is an ele- 
ment of uncertainty in the work, which is not encoun- 
tered with most crops. 

The potato flower consists of a rotate corolla of white, 
lilac or purple petals, five green sepals, five anthers and 
a single pistil. The style projects up through the " cone" 
formed by the closely adhering anthers. The anthers 
open at the tips and give out a small amount of pollen. 
In the day time, the flower is in an erect position, and it is 
impossible for pollination to take place. At night, how- 
ever, the flower bends over and some of the pollen can fall 

1 Journ. Gen., Vol. 1, pp. 7-46. 

2 Illinois Bui. 127. 



Potato Breeding 79 

down on to the stigma. The flowers open in the morn- 
ing and close late in the afternoon. Fruwirth says that 
potato flowers usually give off pollen the second day 
after opening and wilt the third or fourth day. The 
period of flowering for a single plant is between 28 and 
33 days. It seems to be a general opinion that the potato 
flowers are only rarely visited by insects, and that wind, 
also, plays little part in the pollination of the blossoms. 

The first thing to be done in hybridizing plants is to 
decide on a definite ideal. We then choose our parent 
plants with reference to this imaginary type, trying to 
obtain plants which have as many as possible of the 
qualities sought in the new form. 

Generally speaking, it makes no difference which 
variety we use as male and which as female parent. A 
great deal will depend on the nature of the varieties 
themselves. Obviously, we must pick for male parent a 
variety which bears at least a moderate amount of pollen. 

It is well to keep in mind a few general principles of 
hybridization as we proceed. First, the plant to be 
used as female parent should be emasculated to prevent 
its setting seed by its own pollen. This must be done 
before the anthers have matured. Secondly, it is safest to 
bag flowers to be used in crosses, to prevent the entrance 
of foreign pollen. And lastly, the pollen should be applied 
to the stigma when that part is in a receptive condition. 

Mature potato flowers should be examined so that one 
may become familiar with their structure. One should 
learn when the anthers are mature and when the stigma 
is ready for pollination. Just before the bud unfolds 
the flower to be used as a seed parent is opened with a 
pair of fine-pointed forceps. All the stamens are care- 
fully removed, being careful not to break any or to leave 



80 The Potato 

parts of them in the flower. This must be done before 
the pollen is mature. All near-by flowers should be re- 
moved and buds other than those emasculated. As the 
flowers invariably fall off when bagged, this precaution 
must be omitted. The potato is not frequently cross 
pollinated (Salaman) and the danger of contamination 
is slight. It is necessary to tag the flowers thus treated 
in order to know later on when to pollinate them. The 
tag should bear the date of emasculation and other facts 
of which the hybridizer wishes to keep a record. A 
day or two after emasculation, the pistils of the emascu- 
lated flowers should be examined. When the tips have 
turned a slightly darker color and look sticky, they are 
ready to receive the pollen. 

As the pollen is usually borne in small quantities, it 
is well to open the anthers with the point of the forceps 
and scrape it out on to the thumb nail or on to a watch 
crystal. A thin film of pollen on a watch crystal will 
pollinate a number of blossoms. It is customary to make 
two or three pollinations on the same flower in order to 
catch it in a perfectly receptive condition. Once the 
ovary starts to swell, there is little likelihood of the 
flower falling off. The berry should be picked off when 
fairly dry and before it falls off and rolls away. A record 
should be kept of the dates of emasculation and polli- 
nation, and of the parents concerned in each cross. 

Potato seed should be washed free of pulp and care- 
fully dried, in the fall. If left in the pod, it is likely to 
decay. Each pod normally bears from one to three hun- 
dred seeds. The seed should be planted indoors in March 
or April. The seedlings are potted up when they need 
moving, and set out in the field in June. They should 
be planted about two feet apart. 



Potato Breeding 81 

Shoots are sent down into the ground from the axils 
of the first leaves, and it is on these that the tubers are 
borne. As a rule, the tubers for the first year vary in size 
from that of a marble to that of a hen's egg. In unusual 
cases single tubers have been obtained the first year 
which weighed over a pound. Wilson * reports a total 
yield of 6 pounds 3 ounces for a single seedling plant. 

It is often necessary to plant the tubers for another 
year or two in order to secure plants which will bear a 
normal crop of good-sized tubers. The tubers should be 
harvested separately for each plant, put in paper bags, 
and carefully stored until spring. Usually one is able 
to make his final selection the second year, but in some 
cases it is necessary to plant the tubers again before he 
can be sure that his choice of strains is a wise one. The 
tubers should be planted about 40 inches apart the sec- 
ond year to allow a careful study of individual plants. 

One ought to remember that it is comparatively easy 
to produce new varieties of plants, and that the mere 
fact that we have secured new sorts does not mean 
that they are worthy of culture. Any new variety of 
plant should be distinctly superior to others on the mar- 
ket in at least one respect. The markets are already 
cluttered with mediocre varieties. Set your ideals high and 
do not be content with anything which falls short of them. 
Also do not waste time trying to select good qualities in 
strains where no such possibilities exist. Selection will 
not build up characters which are not potentially present. 

In spite of the many hindrances to hybridization, some 
careful studies have been made on the inheritance of 
characters in the potato. We must remember, however, 
that in some cases at least, the material studied was not 

1 Wilson, J. H. High, and Agri. Soc. Scot. Trans. 1907, pp. 74-92. 
G 



82 The Potato 

pure. Perhaps it would be safest to look upon the results 
as showing certain tendencies in heredity, rather than as 
accurate character analysis. Salaman x 2 of England and 
East 3 of this country have done most of the mendelian 
work on the potato. A resume of their work will be given 
in the sections that follow : 

Stem color. — Some varieties of potatoes have pure green stems, 
while others have traces of purple varying from light purple to al- 
most black. The purple seems to be partially dominant over the 
green. The pure greens appear to be recessive and to breed true. 
Salaman 1 found that the deep purple stem color of the Congo gave a 
good mendelian segregation. No ratios were given. 

East (toe. cit.) reports the following : One purple-stemmed vari- 
ety when selfed gave only purples. Four purple-stemmed varieties 
gave both purple and green when selfed. Four green varieties when 
selfed gave only green. A pure green X a heterozygous purple gave 
6 purples and 7 greens — RR X DR. 

Flower color. — Potato flowers may be either white, heliotrope or 
shades of purple. The color is usually confined to one or the other of 
the surfaces of the flower. In all the domestic varieties studied by 
Salaman (loc. cit.) the color was limited to the upper surface. S. tube- 
rosum had color only on the lower surface. In S. verrucosum the 
color appeared to be present on both sides of the flower. 

East (loc. cit.) reports one purple which broke up into 14 purples 
to 5 whites when selfed. He says that purple is probably dominant 
to white. 

Color in the tubers. — The skin of the tuber may be either white 
(yellow), red or purple. The flesh in like manner may be either 
white or colored. Purple-skinned varieties often have white flesh, 
and white-skinned sorts may show traces of color when cut open. 
Salaman l says that these colors are all due to pigments dissolved in 
the cell sap. 

1 Salaman, R. N. The Inheritance of Color and Other Characters in 
the Potato. Journ. Gen., Vol. 1, 1910-11. 

2 Salaman, R. N. A Lecture on the Hereditary Characters of the 
Potato. Roy. Soc. Hort. Journ., 88: 34-39 (1912-13). 

3 East, E. M. Inheritance in Potatoes. Amer. Nat., 44: 424-430 
(1910). 



Potato Breeding 83 

East found that purples when selfed gave in some cases only 
purples; in other cases, purples and whites; and in still others, 
purples, reds and whites. Reds when selfed gave either reds alone, 
or reds and whites. Whites gave only whites. No mosaics of red 
and purple were obtained. The conclusion was that red is epi- 
static to white, and purple, to both red and white. 

Salaman x selfed a red-tubered plant of the variety Flourball and 
got a ratio of 9 reds : 7 whites, suggestive of the action of two pairs 
of factors. He believes that chromogen, a color base, is present in 
all tubers. In the red tubers he assumed the action of an R factor 
for color and a D factor which develops R. The second generation 
would then give : — 

9 RD — red 

3Rdl 

3 rD ) — white 

lrd J 

The red-tubered plant which Salaman self-fertilized was assumed 
to be of the constitution Rr Dd. 

The Congo X Flourball (heterozygous for red) gave in Fi 13 
black : 12 red : 4 white. 

Salaman holds that a factor for purple — P — is necessary in addi- 
tion to the R and D factors to give purple. He has on four different 
occasions united strains bearing white-skinned tubers to get colored 
types. This may be a case of factor interaction similar to Bateson's 
case of complementary colors in the sweet pea. 

Solanuvi etuberosum seems to have an inhibitor to the formation 
of purple in the tubers. 

Flesh color. — Very little work has been done on this character. 
Salaman notes that the color of flesh is inherited independently of 
skin color. He says that colored flesh is apparently due to the 
action of one pair of factors. 

Shape of tuber. — Both East and Salaman found roundness recessive 
to other shapes. Round potatoes bred true in all cases. Salaman 
found that long tubers bred true for long axis, but often varied in 
diameter and hence in shape. Many oval-shaped potatoes were 
found to be heterozygous and to break up when selfed into round, 

1 Salaman, R. N. The Inheritance of Color and other Characters in 
the Potato. Journ. Gen., Vol. 1, 1910-11. 



84 The Potato 

oval and elongated. The kidney and cylindrical shaped tubers have 
about the same length of axis, but seem to have different factors de- 
termining diameter. 

Depth of eyes. — The deep eye is a recessive character and breeds 
true. Shallow eyes are dominant over deep eyes, but often not com- 
pletely so. 

Sterility. — Salaman x finds that a tendency toward sterility is 
dominant over a fertile condition of the pollen. In a cross of Record 
(no pollen) X Flourball (abundant pollen), the Fi generation gave 
12 pollen-bearing plants and 20 with no pollen. One of the sterile 
(for pollen) Fi plants crossed with the male parent used above gave 
19 pollen bearing to 20 non-pollen bearing. This is practically the 
1 : 1 ratio which we should expect to get from a cross between a 
heterozygous and a pure recessive. 

Stolon length. — The stolons on which the tubers are borne are un- 
usually long in the species, S. Commersonii and S. verrucosum, often 
reaching 6 feet or more. In the domestic varieties the stolons 
average 9-12 inches. Very long and very short stolons breed true. 
Intermediate stolons break up into various lengths, suggesting the 
action of multiple factors. Salaman * thinks there may be two or 
perhaps three pairs of factors involved. 

Plant habit. — Salaman 1 states that upright and prone habit of 
plant are due to the action of one pair of factors. A duplex condi- 
tion of the factor for uprightness gives a perfectly upright plant. 
Heterozygotes, Aa, are upright at first, but droop toward the close 
of the season. Prone plants have the constitution aa. Both prone 
and upright plants bred true to type. Intermediates gave a ratio 
of 1 upright : 2 intermediates : 1 prone, when selfed. 

Shape of berry. — The seed berries of domestic varieties of pota- 
toes are round. Those of the wild species tend to be long. Salaman 
concludes that one pair of factors is involved. He believes the long 
berries to be due to a duplex dose of a factor for length. When the 
length factor is simplex, a heart-shaped berry results. The double 
recessive factor gives round berries which breed true to shape. 

1 Salaman, R. N. A Lecture on the Hereditary Characters of the 
Potato. Roy. Soc. Hort. Journ., 38 : 34-39 (1912-13). 



Potato Breeding 85 



REFERENCES 

East, E. M. A Study of the Factors Influencing the Improvement 

of the Potato. 111. Bui. 127, 1908. 
East, E. M. Inheritance in Potatoes. Amer. Nat., 44 •' 1910, pp. 

424-430. 
Fraser, S. The Potato. N. Y. (Orange Judd Co.), 1-185, 1901. 

Breeding and Selection, pp. 171-177. 
Fruwirth, C. Die Zuchtung der landwirtschaftlichen Kultur- 

pflanzen. Vol. 3, Berlin, 1905. 
Newman, L. Plant Breeding in Scandinavia. Ottawa (Can. Seed 

Growers Association), 1912, pp. 193. (Potatoes, 168-182.) 
Salaman, R. N. The Inheritance of Color and Other Characters in 

the Potato. Journ. Gen., Vol. 1, 1910-11, 7-46, pis. I- 

XXIX. 
Stuart, Wm. Potato Breeding and Selection. U. S. D. A. Bui. 195 

(professional paper), 1915, pp. 35, pis. XVI, figs. 
Waid, C. W. Results of Hill Selection of Potatoes. Amer. Breeders 

Association, Ann. Rept., Vol: 3, 1907, pp. 191-199. 
Webber, H. J. Methods of Breeding and Improvement of the 

Potato Crop. Cornell Farmers' Reading Course Bui. 43, 

1909, pp. 753-768. 



CHAPTER V 

CLIMATE, SOILS AND ROTATION 

By Daniel Dean 

The climate of most parts of the United States is not 
well suited to the production of the potato. The heat of 
summer is too great and the water supply in the soil and 
in rainfall during the growing season is too small. It is 
not known what are the possibilities of the potato in the 
mountain regions of South America from which it was 
brought by white men in the sixteenth century, but it is 
certain that up to the present time growers of north- 
western Europe have often secured higher yields to the 
acre than those of the United States. One great reason 
for this fact is the difference in climate. The most famous 
potato-growing regions of Europe are several degrees 
north of any part of the United States, except Alaska. 
The average summer heat of northern Germany is esti- 
mated by the United States Department of Agriculture at 
nearly ten degrees Fahrenheit lower than that of most of 
the potato-growing sections of the United States. The 
climate of the principal potato-growing regions of Europe 
is so cool that Indian corn is not grown in them, while 
there is heat enough for corn in most of the northern 
United States and even for cotton in the South. Most 
of northwestern Europe has very heavy rainfall because 
of the Gulf Stream. The potato is grown in the United 

86 



Qlimate, Soils and Rotation 87 

States because of its high value for human food, not be- 
cause of favorable conditions. These facts are emphasized 
because knowledge of the nature of the potato plant helps 
the grower to adapt his methods to his local conditions 
to secure the best results. Except in northern Maine 
and the adjoining provinces of Canada, there are few 
parts of America where summer heat and moisture do not 
limit the yield of the potato to a figure below the best 
possibilities of the plant. Methods which prevent the 
effects of these two factors result in largely increased 
yields. In occasional seasons, as in parts of New York 
in 1909 and 1914, the climate is favorable and large yields 
are grown. It might be possible in such years to get 
yields equal to those of northwestern Europe, but it 
would be necessary to equal their large expenses for addi- 
tional labor, seed and fertilization and this would result 
in heavy loss in the other years when climate limited the 
yield. Hot and dry years are known in Europe, but are 
the exception instead of being the rule as in most of the 
United States. 

The United States Department of Agriculture Year- 
book for 1914 gives the average yield of potatoes to the 
acre for the whole United States for ten years as being 
96 bushels, while that of the state of Maine, with cool and 
damp climate, for the same period, was 206 bushels. 
The figures for the countries of northwestern Europe are 
311 for the Netherlands, 388 for Belgium, 210 for Great 
Britain and Ireland and 200 for Germany. Yields are 
lower in the warmer or drier countries of Europe, being 
130 in France, 115 in Hungary and 106 in Russia. A 
similar contrast is marked between hot Australia with an 
average of 101 bushels and cool New Zealand with 216, 
though both are settled by the same race of people. 



88 The Potato 

The warmest province of Canada, Ontario, averages 121 
against 207 for the cool and moist maritime provinces 
and 229 for British Columbia. 

Land is much higher in price in the potato-growing 
regions of Europe than in America. An extreme case is 
on the Island of Jersey, where land is worth $1000 to 
$2500 an acre. The annual rental under the tenant sys- 
tem common in Europe is often higher than the sale 
value of an acre in sections of the United States which 
raise millions of bushels each year. Labor is much 
cheaper in Europe than in America, allowing the use of 
very intensive hand culture at low cost. If European 
growers are to secure a living profit above their high 
rentals, they must farm this high-priced land very inten- 
sively with large expenditure of cheap labor, seed at 
the rate of an average of over 37 bushels to the acre and 
heavy fertilization. 

American agriculture has been developed in the direc- 
tion of heavy production to each worker engaged rather 
than in that of large yield to the acre. The high-priced 
day's work is the unit, not the high-priced acre of land. 
From the time when the Massachusetts Bay colonists 
"went west" to the Connecticut Valley in 1635, it was 
necessary to go westward, even to northwestern Canada, 
for there has been a new region of cheap land awaiting 
settlement. Almost until the present time, the competi- 
tion of new soil of virgin fertility has kept down the price 
of farm produce and of land in the older settled communi- 
ties to figures far below those of Europe. An even worse 
effect of this competition has been that little attempt has 
been made to keep up soil fertility. Methods of farming 
suited to frontier conditions of low prices and highly 
fertile soil have continued in use too long. Land is now 



Climate, Soils and Rotation 89 

rapidly rising in price, and methods of increasing the yield 
of crops will become more important than before. 

The high cost of labor in the United States compared 
with that of land has resulted in the invention and use 
of labor-saving machinery for nearly every process of 
farming by which the power of horses or of engines has 
displaced that of human muscle. Machinery cannot so 
much increase the production to an acre as the production 
to each worker engaged in farming by increasing the num- 
ber of acres farmed by each. For example, the use of 
horse-drawn tools compels a wider spacing of potato 
rows than where most of the work is by hand labor. 
This reduces the yield to the acre by reducing the num- 
ber of plants. On the island of Jersey, rows of potatoes 
are spaced 16 inches apart and 24 to 27 in other parts of 
Europe, compared with 33 to 42 in America. 

FACTORS INFLUENCING POTATO CULTURE 

Study of the factors governing the choice of methods 
for the culture of the potato shows that eight are of prin- 
cipal importance: (1) heat in air and soil; (2) water; 
(3) soil texture ; (4) available plant-food ; (5) drain- 
age and soil air; (6) the "critical period" in the life of 
the plant ; (7) type, variety and strain of the seed ; 
(8) diseases. 

The term "limiting factor" is frequently used in other 
connections and is peculiarly appropriate in potato- 
growing. Any one of the above factors may be inhibiting 
in some conditions and may be able to place a limit on 
the size of the crop which cannot be removed by the 
others being favorable. For example, all farmers are 
familiar with the loss of yield caused by drouth, although 



90 The Potato 

not all know that the direct effect of great heat is per- 
haps even more harmful than the lack of water. The 
results of unchecked attacks of insects like the Colorado 
potato-beetle or of the late blight and rot, are other 
familiar examples. The potato-grower who would raise 
good yields every year through a series of years must 
study very carefully every factor which enters into the 
growing of potatoes under his particular conditions, 
with the idea of making sure that no one condition 
will limit the results of his labor in other directions. 
Such care counts heavily in increasing the income of the 
farm, because seasons in which a crop is generally poor 
from any cause are the ones in which prices are high. 

Heat 

Numerous experiments have shown that temperatures 
in the soil above certain limits injure the vitality of the 
potato plant. The extent of the injury depends on the 
degree of heat and on other injurious factors, as drouth 
and insect injury. The effect varies from reduction in 
yield to practical failure with tubers ruined for use as 
seed. Potatoes are not grown in the South in midsum- 
mer. When grown in the months of late winter and spring, 
the vitality of the tubers for use as seed is ruined by the 
heat at the time the tubers mature. The " second-crop " 
for seed in the South is planted in July or August and 
forms its tubers in the cool weather of late fall. At this 
time seed of good vitality is obtained. Near the Canadian 
line and in the Rocky Mountain region there is little more 
time in the whole growing season than is needed by the 
late main-crop varieties. When hot seasons occur there, 
as at Ottawa, Canada, in 1906-7-8. and at Greeley, Colo- 



Climate, Soils and Rotation 91 

rado, in 1911, there is no way of avoiding the heat by 
early or late planting. In intermediate sections like those 
from Long Island through to Iowa, growers avoid the 
effects of summer heat to some extent by planting 
either very early or very late. 

Another method used more or less unconsciously by 
growers to prevent the effects of summer, is the use of 
heat-resistant varieties. The McCormick or Late Hoosier 
is used in Virginia and Maryland in summer because of 
its peculiar ability to produce crops in weather too hot 
for any other variety. The Rural or Blue-Sprout type 
is the one which is grown more than any other in the 
United States. It owes much of its popularity to the 
fact that it will yield well in hot and dry seasons. The 
use of the Green Mountain or White-Sprout type is 
mainly confined to the cooler sections, like Maine, because 
of its inability to stand heat as well as the Rural type. 
The Triumph, Cobbler and Early Ohio types are used to 
avoid extreme heat by growth in early spring rather than 
by heat resistance. 

Heat is such a decisive factor in the growth of potatoes 
in most of the United States that growers must ever keep 
its effects in mind if they are to succeed with the crop. 
Many of these methods of culture now used have been 
forced on growers unconsciously by the influence of heat 
on the plant. Much is to be expected in the future from 
further investigations. Straw mulches have been found 
very beneficial in the hot regions of the western plains to 
insure coolness in the soil. It has been proved that 
thorough spraying with bordeaux mixture greatly reduces 
the injury from heat. This is shown by some of the 
gain from spraying in hot seasons when blight and insect 
injury are absent. A possibility is in the use of over- 



92 The Potato 

head irrigation in humid sections. One of the greatest 
needs of potato-growers everywhere is a new variety 
possessing the table quality, yield and appearance of 
those now in use together with the heat-resistance of the 
McCormick. 

Water requirements 

Lack of sufficient water is often a limiting factor on 
the yield of potatoes. Many experiments indicate that 
about 400 tons of water are used by the potato plant for 
each ton of dry matter produced, or over three tons for 
each bushel. This equals 3 inches of rainfall for each 
100 bushels to the acre. Study of Weather Bureau 
records of rainfall shows that the average amount in the 
entire growing seasons in most potato-growing sections 
is only 10 to 18 inches. The losses from run-off and 
from evaporation are so heavy that this factor must 
be provided for if exceptional yields are to be raised. 
Methods of conserving the soil water left by winter rains, 
for the use of the crop, are of great value. The use 
of ordinary surface irrigation in the West and of over- 
head irrigation in the East produces much heavier yields 
than when rainfall is the whole dependence. With these 
methods, yields of over 500 bushels to the acre are common. 

Surface tillage to prevent evaporation and the incor- 
poration of organic matter with the soil are the principal 
means of conserving moisture. Plants on rich soil or 
when manures or fertilizers are used, are able to secure 
their plant-food from the soil by the use of less water 
than when grown on poor soil. Any means of extend- 
ing the growth of roots makes more water available. 
The great need of water for the potato crop comes at the 
time when the tubers are forming. It is a matter of 



Climate, Soils and Rotation 93 

common observation that a small amount of rainfall at 
this time may be worth much more than larger amounts 
at other times. As this comes immediately after the 
critical period in the life of the potato, it will be seen that 
every effort should be made to keep the plant well sup- 
plied with water by tillage, organic matter, and the like. 

Soil texture 

The root system of the potato is weak and small com- 
pared with that of other standard farm crops, such as 
corn. It is especially weak in penetrating heavy soils. 
In any soil, loose texture greatly favors the potato by allow- 
ing wider and deeper distribution of the roots. The de- 
velopment of the tubers is checked and rendered irregular 
unless the soil is loose and open in texture. Most of the 
early crop for sale in summer is grown on sandy soils. 
On account of their advantages in structure, potatoes would 
be raised only on sandy soils did they not have other dis- 
advantages which offset the value of good structure and 
earliness. Too great soil heat and lack of moisture often 
limit the yield of potatoes grown on sandy soils as a late 
main crop in summer. Much of the work of the potato- 
grower must be directed to give heavier soil types a struc- 
ture more loose and open. Increasing the proportion of 
organic matter loosens up the structure of soils. Some of 
the greatest potato-growing soils naturally possess plenty 
of organic matter, as the Aroostook soils and the tule 
lands of California. The increased value of irrigated 
soils for the potato-growing where organic matter is sup- 
plied by rotation with alfalfa, or the use of humus-produc- 
ing cover crops in the South, shows the importance of or- 
ganic matter. There are few American soils which are not 



«)l The Potato 

iiiii>io\ a\ for i he potato by increasing their organic tnal ter 
content. Under most American methods of cultivation 
the proportion is reduced; consequently yields are grad- 
ually reduced, and in the case of some varieties, like the 
Burbank, even the shape of the tubers may be injured 
by development in the less mellow soil. Cheap and easy 
methods for the increase <>l' the supply of organic matter 
are among the greatest nerds of potato growers, 

. [writable plant-food 

For several reasons the potato is less able to secure its 
plant-food from the soil as well as man.} other plants un- 
less il is in readily available condition. Por example, the 
use of insoluble phosphoric acid in Hie form of raw rock 
phosphate often gives good results on oilier crops but 
seldom on the potato. A large supply of organic matter 
in the soil, good drainage and a slightly alkaline condition 
are essential io the liberation of the stores (A' plant-food 
in the soil for the use of plants. Fertilizers do not pro- 
duce their full effect on potatoes unless these conditions 
are present. If the latter are favorable, fertilizers seldom 

fail to increase the yield. The use of ferl ilizers on potatoes 
is increasing very rapidly. In Maine, Long Island, New 
Jersey and through the coast trucking section from Nor- 
folk to Florida, over a ton to the acre is often used. The 
value o\' potatoes lor human food is so high (hat the price 
received for the crop makes such use profitable. There is 

also a residual effect of the fertilizer on the succeeding 
crops of a rotation, to he considered. Part of this cWa-t 
may be due to a favorable effect of fertilizers on the soil 
bacteria. 3 

I l'. S. I>. A Oil. uf Exp, Sta, Ilui. 194, 



Climate oil and Rotation 95 

Vra/mage and soil a/i/r 

AJJ crops require mor< oj J' . ah in thi soil for hi 
and growth. The need of air in the soil is one r< 
why potatoei do poorlj on too heavy clay .oil., . - 
rea son for the ridge culture so much u ed oj 
soils like those of the Aroo tool region and the rolusia 
soils regie tin need of drainage and soil air. Air is 
;." ' . : to 1 of bacteria in the soil and to 

chemical changes which make plant-food available in 
it. Water is nec< ■ .■ to plant \ ■ too much 

in the soil is injuriou Tile-draii 
plus of water qui* and o i ' ■ i 

ward the area in which roo ci i extern potato- 

learned to apply tbi 
furrows betwe< the row The row are ridg< 
enough to alio// the forming tubers and a 

// . tern to r« main above the level of tin 
the furrows. The potato us very sensitivi 
of too much water in the -.oil. This i own b 
quickness with which potatoes die after b< 
by floods or by standing water aft< i - be immer- 

ioj oj - he ' op for i • .. < . oi i ein ho u i i fatal. 
'J oo .•■'. •' in the .oil will kill ■.. n o - rool • nd 

the vitality of the planl 

Critical period 
'J he potato i not . • ■ dim 

and the se mall. 'Hie p 

been produced from the original ■• by hun- 

dred v eai o - • 



96 The Potato 

mands now made upon the plant. The yield of tubers 
has been enormously increased above that of the wild 
plant. Many shapes and colors have been discarded to 
keep the few which suit the eyes of civilized men. The 
length of the life of the potato plant has been shortened 
from nine months or more in the wild state to only three 
or four months. Vast numbers of seedling varieties 
which may have possessed greater natural vigor have 
been discarded to keep those which possess these quali- 
ties. It is not surprising therefore that the potato plant 
is not a strong one. One period in its life is especially 
precarious. The cultivated plant now produces much 
less seed than the wild plant, some kinds seldom or never 
blossoming; but blossoming is still a demand upon the 
strength of the potato. In the wild state the tubers were 
set after the seed formation. Under domestication the 
life of the plant has been shortened and the two processes 
overlap. When this time comes in hot weather, as with 
the late main crop of the northern states, the heat and 
drought which occur so often make the poorest possible 
conditions for the potato. Insects, diseases and careless 
methods of cultivation often further reduce the vitality 
of the crop. This has been called the "critical period" 
of the life of the potato. If it is passed in high vigor, the 
potato has later a more or less indeterminate growth. 
That is, there is no clearly defined time for its maturity, 
as with grain crops, but instead it gradually weakens, all 
the time increasing the yield of tubers. This condition 
occurs but seldom in the United States on account of the 
heat of summer, but it is an ideal towards which potato 
growers should strive. Production of a high degree of 
vitality in the growing plant in its early life and good 
soil conditions and care during the hot weather, will carry 



Climate, Soils and Rotation 97 

the crop safely through heat and drought which would 
not only badly reduce the yield but also spoil the crop 
for use as seed. Practically the whole yield is produced 
after this time. 

Type, variety and strain 

In this chapter, reference to the seed used is made to 
show that the variation between different types, varieties 
and strains allows the grower considerable latitude in 
adjusting the potato crop to different conditions. The 
use of quickly maturing types in the South and of heat- 
resistant types in all but the most northern sections are 
examples of these adaptations. Much effort has been 
expended in the effort to find new varieties possessing the 
quality of resistance to some of the more serious potato 
diseases, but with little success as yet. 

Diseases 

Several of the most important potato diseases affect 
cultural methods. Examples of such are the use of long 
rotation to eliminate common scab, rhizoctoniose, the 
nematode eelworm and the fusarium wilt, from affected 
soils. Early spring planting to insure maturity before pos- 
sible attacks of late-blight is employed in some sections. 

GENERAL TYPES OF POTATO-GROWING IN THE UNITED 

STATES 

Conditions of climate, soil, seed and markets vary so 
much that every grower has his problem to select the 
methods which will give him the most profitable results. 
The climate is something the grower cannot change. 



98 The Potato 

The markets have demands which the individual can do 
little to change. But in the selection of methods he has 
wide range of choice. The great variation in the climates 
and soils of as large a country as the United States makes 
for a wide range in culture methods. Broadly speaking, 
most of the potato-growing of the United States may be 
divided into five general types : 

(1) The early truck crop of the southern states, extend- 
ing to about the latitude of Washington. This belt is 
characterized by extreme summer heat which prevents 
growth in summer, excepting that of the heat-resistant 
McCormick variety. The crop is grown in the cool 
months of winter and spring for shipment to city markets 
because too perishable to store in the hot summer. Most 
of the seed is imported from the north or grown in the 
cool fall months as a "second crop." Commercial fer- 
tilizers are heavily used in this belt. The summer heat 
does not permit growth of most of the perennial hay crops 
used in other sections. Annuals are mainly used for hay 
and for the cover-crops that are often raised to prevent 
erosion and loss of plant -food in winter. Owing to the 
higher prices for extreme earliness, only short -season early 
maturing varieties are used and these are usually dug 
immature. Less machinery is used than in other sections. 

(2) The northern belt of the principal potato-producing 
states. This extends from Maine to North Dakota and 
down to the latitude of New York City. This belt sup- 
plies the cities and southern states during the fall and 
winter and competes with the southern truck crop from 
April to July. The climate here is cool enough for the 
potato to maintain its vitality in most seasons, if given 
good care. Early varieties are now grown but little 
except for shipment South as seed stock. The use of fer- 



Climate, Soils and Rotation 99 

tilizers is steadily increasing, being very heavy in the 
East from Maine to New York. Spraying with bordeaux 
mixture for the late blight and rot is prevalent in the East. 
Digging comes so near to freezing weather that the grain 
crops grown in rotation with potatoes are those sown in 
spring. Oats are used mostly with spring wheat in the 
Red River section. Oats and peas and barley are grown 
to less extent. 

(3) An intermediate belt between these two from 
Nebraska to New Jersey and Long Island. Potatoes 
from this belt come on city markets in summer and early 
fall, part being stored for winter shipment. Summer heat 
is not so dangerous as in the South, but there is usually 
an effort to avoid its effects to some degree either by 
planting early enough to get the crop nearly mature 
before midsummer or else late enough to have much of 
the growth come in the cool fall months. The effect of 
summer heat on seed vitality is often severe, but a large 
share of the seed is grown locally. The use of imported 
seed from the North is increasing, particularly in the 
regions of more intensive culture, such as Long Island. 
Winter wheat and rye often follow the potato in rotation 
in this belt. 

(4) The irrigated sections of the West, destined to 
great extension in the future. The problems of the 
potato-grower in other sections are here largely replaced 
by those peculiar to the growth of the crop under irriga- 
tion. New systems of culture have been worked out to 
meet the new conditions. Control of moisture has en- 
abled some of the heaviest yields ever grown in the 
United States. Owing to the natural high fertility of 
arid soils, fertilizers are unknown. Nitrogen and organic 
matter are secured by rotation with alfalfa. 



100 The Potato 

(5) Potato-growing by the so-called dry-farming methods, 
and local conditions such as the delta section of California, 
are as yet less important types. 

SOILS 

The choice of the soil on which to grow the potato is 
peculiarly difficult because of the fact that those which 
best meet the needs of the plant in one respect may be 
unfitted for it in others. Sandy soils permit free develop- 
ment of the root system, are well drained and are capable 
of early tillage in spring. Although usually poor soils 
unless fertilizer is applied, the growth of the crop is rapid ; 
and for these reasons most of the early truck crop of the 
South is grown on sandy soils, as earliness secures the 
highest prices. The great problem of potato-growing on 
sandy soils is that of sufficient water supply at the time 
the tubers are forming. This tendency to drought and 
heat injury of the crop has operated to lessen the use of 
sandy soils in the northern states for the late main crop 
in favor of soils cooler and more retentive of moisture. 
A large proportion of organic matter is of great value to 
sandy soils in increasing available fertility and the ability 
to hold moisture. The organic matter in sandy soils is 
easily exhausted by tillage, and constant effort is needed 
to keep it up to a high standard. 

The larger part of the potato crop of the United States 
is grown on soils ranging in texture from sandy or gravelly 
loam to clay loam. Such soils are capable of holding 
enough moisture to supply the growing plant continu- 
ously, are cooler than the sands, and are usually of fair 
fertility if not too deficient in organic matter. While the 
extension of the roots and the formation of the tubers 





Plate VIII. — Seed potatoes. Top, different ways of cutting. 
torn, good and bad types for seed. 



Bot- 



Climate, Soils and Rotation 101 

are not as easy as in sandy soils, these types are not heavy 
enough to prevent success with the potato. Clay soils 
are too hard and heavy for the potato. Too much water 
at times and poor ventilation often affect the health of 
potatoes on clays. Careful tillage, tile drainage and the 
incorporation of organic matter lighten clay soils until 
they will produce good crops of potatoes in most years. 
Except in special cases, as near-by markets, it usually 
pays better to grow potatoes on lighter soils and use the 
clay soils for crops more adapted to them, as grass. 
Muck soils, as the tule lands of California, often produce 
large yields of potatoes. The quality is likely to be poor. 

The importance of organic matter in the soil is seldom 
fully appreciated by American farmers. Most American 
soils outside of the arid regions contained more organic 
matter when first brought under cultivation than now. 
The gradual depreciation from year to year is not noticed 
until heavy loss in fertility has occurred. Another cause 
which has contributed to the depreciation of American 
soils is the low price of farm produce. The Department 
of Agriculture estimates the cash labor income of Ameri- 
can farmers to average about $320 a year besides the 
items secured from the farm as house-rent, garden, and 
the like. Too often this condition leads to robbery of 
the farmer's capital, the soil. The settlement of the last 
free land has led to a rise of the prices of farm products, 
which now makes it profitable to replace and increase the 
lost organic matter and lime fertility of older soils. 

Organic matter has great power to absorb water and 
hold it for the use of plants. The potato is very sus- 
ceptible to injury from lack of water, making this property 
of organic matter of great value. The physical nature of 
any soil is greatly changed by organic matter. Heavy 



102 The Potato 

soils are lightened, often to a degree which insures 
success instead of failure with the potato. Sandy soils 
are improved by their particles being bound together. 
The presence of abundant organic matter makes the soil 
more healthy as a home for plants and for the beneficial 
soil bacteria. Both need water and air. The plant-food 
in the organic matter is in condition to feed the crop as 
fast as it decays and breaks down. Indirectly the decay 
helps to dissolve the mineral plant-food in the soil. 

Many kinds of bacteria and other microscopic forms of 
plant life are found in the soil. Their action and value 
are seldom understood by farmers. Too often the word 
"bacteria" conveys only the idea of disease, or at most 
that of the particular bacteria associated with legumes 
to take nitrogen from the air. These latter form but a 
fraction of the microscopic life of the soil, part of which 
is beneficial and part detrimental. Organic matter in 
and on the surface of soils is the food of many kinds of 
bacteria, and is broken down by them to forms which 
plants can assimilate. The nitrogen of organic matter 
is changed first to ammonia and then to the soluble 
nitrate form. Other bacteria like the azotobacter group 
take nitrogen directly from the air without being asso- 
ciated with any particular plants. The solution of 
mineral plant-foods is helped by some kinds of bacteria. 
The statement is generally true that the fertility of a soil 
varies according to the number of bacteria present. The 
number of the beneficial forms is increased by attention 
to maintaining the best conditions for their growth, as a 
large supply of organic matter for their food, an alkaline 
soil, sufficient water but not too much, and sufficient 
soil air. 

Organic matter in the soil is of so great importance to 



Climate, Soils and Rotation 103 

the potato crop that methods for maintaining its supply 
need careful study. In the natural wild state the soils 
of humid regions receive constant additions of organic 
matter from the death of plants and the leaves of trees. 
The richness of newly cleared forest land and of the west- 
ern prairies when first broken are examples familiar to all. 
Under cultivation most crops annually produce more 
organic matter than do wild plants, but in most cases only 
a fraction is returned to the soil. Part is shipped away 
from the farm for the use of man or of animals, part is 
destroyed by the animals fed on the farm in the process of 
digestion and part is lost in handling the manure. Opera- 
tions of tillage and exposure of bare soils to the air rapidly 
use up organic matter. A few American soils are being 
handled in ways which increase their organic matter, but 
most of them probably are not. 

The principal method of maintaining soil organic 
matter is that of crop residues. All crops leave part 
of their organic matter in the soil after being harvested, 
the proportion varying greatly. When potato tops are 
burned to prevent disease, very little organic matter is 
left in the soil from the roots. Other plants have more 
extensive root systems and also leave other residues in 
the form of stubble. A larger proportion is left when 
only the grain or seed of crops is removed and all stalks 
or straw is left on the land. Feeding off crops in the 
field, as in "hogging down" corn, leaves all the organic 
matter except that destroyed in the process of digestion. 
In practice, hay crops leave more residues than others 
like grain and potatoes. It is unfortunate that so little 
attention has been paid to hay crops in the United States 
compared with that given to the inter-tilled crops and 
to the grains. Tillage, manure, fertilizer and care are 



104 The Potato' 

too much concentrated on the other crops of a rotation 
and the hay is left to grow as best it can. The handling 
of meadows and pastures is far better understood in 
Europe than in America, some being hundreds of years 
old. The use of better seed mixtures, of better methods 
of seeding, of better adaptation of the different hay crops 
to soils and of better fertilization will not only add directly 
to the yield and value of hay crops, but will increase 
greatly the yields of the other crops of any rotation by 
increasing soil fertility. 

The statement is often made that when farm crops are 
fed to animals, the entire crop is returned to the soil in 
the manure. This is nearly true in regard to the mineral 
elements when the manure is well cared for. But the 
organic matter is very largely lost in the process of diges- 
tion. Over sixty per cent of that of hay and straw is 
used in this way, somewhat less in the case of grain feeds. 
In addition there is the loss in the handling of the manure. 
While the remainder is in more quickly available condi- 
tion than in straw or in stubble, the question of whether 
to harvest the crop to feed or to return directly to the 
land will depend on the profit expected from feeding, the 
need of the soil for organic matter, the cost of labor and 
the effect which either practice will have on carrying out 
the rotation in use. The millions of people in cities must 
be fed. The organic matter and mineral plant-food in 
the produce shipped is lost to the farm, but other means 
can be found of replacing both. The price of farm prod- 
uce within easy shipping distance of cities is often greater 
than its value as feed for animals on the farm. Under 
these conditions it pays to sell crops and keep up soil 
fertility by fertilizers, catch-crops, and by attention to 
increasing crop residues left in the soil. Prices for farm 



Climate, Soils and Rotation 105 

produce are now high enough so that this can be done. 
The great danger which the history of American farming 
has shown is that the temptation to sell off cash crops 
too closely is so great that attention to maintaining fer- 
tility is put off too long. Animal husbandry has the 
advantage in practice that the return of the manure to the 
soil is a necessary part of farm work and soil robbery is 
less likely to result. 

The third way to return organic matter to the soil is 
to return the entire product of any crop. Any crop may 
be used for this purpose, although, in practice, those used 
are usually of low cash value. Great need of soil organic 
matter and increase in yield incident to such a valuable 
cash crop as the potato may make it advisable to plow 
under crops like clover which would be inadvisable in 
other crop rotations of less value. The term "green- 
manure" refers to crops plowed under before maturity. 
The term "catch-crop" refers to one grown between 
crops raised for sale or feed or for other uses. The term 
"cover-crop" is usually restricted to those grown to 
occupy the soil during the winter. In addition to supply- 
ing organic matter, any of these may cover and protect 
the soil and so prevent losses by erosion and leaching. 
A crop plowed under while still green and immature, and 
which contains such a large proportion of water that it 
decays quickly, may give only a small net gain over the 
cost of seed and planting and the amount of organic 
matter destroyed by tillage. Green-manures must be 
used with caution wherever their use is likely to reduce 
the soil moisture for the following crop. Rye plowed 
under in spring is often injurious in this way. The 
amount of water needed for large crops of potatoes is so 
great that early spring plowing or surface tillage is usually 



106 The Potato 

advisable to save as much moisture as possible for the 
potatoes. Another danger from the use of any form of 
organic matter plowed under shortly before planting is 
that movement of the soil water may be hindered and 
the plants injured for lack of it. So much of the money 
value of grain crops is in the seed that it usually pays to 
harvest the crop, sell or feed the grain and return the 
stalks or straw only to the soil. Many experiments have 
shown that the amount of organic matter in any crop 
increases most rapidly in the latter part of its life ; so 
that in the straw of a grain crop there is likely to be found 
more than that in the whole crop if plowed under a few 
weeks before maturity. The value of the grain is several 
times the cost of harvesting and threshing. The use of 
the hay crops seeded with the small grains to plow under 
gives larger net returns of organic matter to the soil, 
because, unlike rye, buckwheat, or soy beans, there is no 
destruction of organic matter by tillage in planting. 

The need of winter cover-crops for soils is least where 
the ground is constantly frozen or covered by snow 
throughout the winter. Mild and open winters, as in 
the South, make it desirable to have the soil covered by 
plants which will prevent erosion and save plant-food 
which would otherwise leach away. Unless left to grow 
too long in spring, there is little danger in humid sections 
of loss of enough water to injure later money-crops like 
potatoes. 

The choice of catch-, cover- and green-manure-crops 
for any particular rotation, soil and climate depends on 
many factors which differ from those governing the choice 
of the money-crops of the rotation only because cover- 
crops seldom have a cash value. Those crops of any 
rotation which have the greatest value, as is generally the 



Climate, Soils and Rotation 107 

case with potatoes, naturally govern the choice of others 
to a great extent. The degree of its adaptability to soil 
and climate, ability to fit into Rotation with other crops, 
money value, net increase or decrease in soil fertility, and 
cost of growing are all to be considered. 

ROTATION 

It is seldom desirable to grow the potato continuously 
on the same soil. The reasons for the rotation of the 
potato with other crops are : (1) Plant diseases often 
rapidly become worse when crops are grown continuously. 
This has often been the case with the potato. Modern 
scientific methods of care of seed, selection, disinfection, 
spraying and other details of culture somewhat reduce 
this danger. (2) In the business management of the 
farm, rotation reduces the danger of excessive losses in 
seasons of low prices or of poor yields, and arranges the 
work of the farm through the season to better advantage. 
(3) Weeds are easier controlled under a system of rota- 
tion. Those which flourish under the conditions of 
growth of one crop may be easily kept down under an- 
other. The high value of the potato crop pays for 
thorough tillage and care which cleans the soil of weeds 
for the rest of the rotation. (4) Insect pests are kept 
down easier under rotation. (5) The high cash value of 
potatoes justifies considerable sums of money spent on 
fertilizers and enables more of the time of the rotation 
to be used in producing organic matter to be returned 
later to the soil. The thorough culture, late digging and 
winter exposure of soil after potatoes in the northern 
states rapidly uses up the soil organic matter. The 
cheapest and easiest way of replacement is by rotation 



108 The Potato 

with grass, clover and other hay crops which have a money 
value as food for animals, and also leave large amounts 
of organic matter in the soil from their roots and stubble, 
as well as that in the manure from the hay fed. Legumes 
are able to draw part of their nitrogen from the air to 
increase the soil supply. Some nitrogen is also obtained 
from the air in other ways, as by the non-symbiotic 
bacteria. This is shown by the great fertility of the wild 
prairie soils which have had few leguminous plants. 
(6) Different plants draw on the plant-food in the soil 
in varying proportions. Consequently a rotation of crops 
enables each to secure its plant-food easier than it would 
if grown continuously. (7) Though the potato sends its 
roots deeper than some crops, there are others, like clover 
and alfalfa, which root much deeper. These bring up 
fertility from the subsoil, and the roots of potatoes follow- 
ing are able to grow lower, even in hard clay soils. 1 (8) It 
is believed that plants throw off in the soil in their growth 
toxic substances which by accumulation become injurious 
to succeeding crops of the same plant but not to others. 
(9) The physical condition of the soil for succeeding crops 
is improved by the thorough culture given the potato. 
Instances of this are the use of wheat following potatoes 
without plowing in fall, and oats without plowing in 
spring. 

The net return of the rotation as a whole must be the 
deciding factor in the choice of crops. The potato gives 
such large cash returns to the acre and responds so well 
to the use of fertilizers that it is usually the most important 
crop of the rotation in which it is grown. Wherever this 
is true, the choice of the other crops to go with it is largely 
governed by their effect on the soil for the production of 

1 Colo. Bui. 216. 



Climate, Soils and Rotation 109 

the potato. In the northeastern states the most common 
rotation is one of a tilled crop like potatoes or corn the 
first year, a small grain crop usually oats or wheat the 
second year, in which grass seeds are sown. In regions 
of the most intensive culture, this hay crop is cut only 
one year and in that case it is clover. In others the mix- 
ture is clover and timothy with occasionally redtop, which 
is cut several years. Further South, where grasses do 
not grow well, it is necessary to use annual hay crops like 
crimson clover or cowpeas. In the North grass seeds 
are seldom sown alone. The practice of summer tillage 
before sowing alfalfa has been found so valuable that it is 
coming into use for the sowing of the grasses as well, 
particularly on weedy soils, or on those on which it is 
difficult to get seeds sown with grain to catch. 

The relative profit to be expected from the growth of 
potatoes, grain and hay determines the number of years 
which each will use in a given rotation for any locality. 
In New England hay and potatoes are both relatively 
more valuable than grain, and each may occupy the soil 
for two years out of a five-year rotation. In New York 
and Pennsylvania the hay may be cut for several years. 
Going South, hay is grown less and less until in the truck- 
ing section potatoes are rotated mainly with other truck 
crops as spinach and cabbage. In the middle West the 
higher cost of transportation of potatoes and hay com- 
pared with grain causes the latter to be grown several 
years in a rotation, as is often the case in the Red River 
section. 

Hay plants 

Alfalfa is the best crop to rotate with potatoes where 
it can be grown with profit, as in the Rocky Mountain 



110 The Potato 

region. It is a perennial, is deep-rooted, produces several 
cuttings to distribute labor and risk of bad weather 
through a longer period, yields heavily, is of high value 
for either feed or sale, gets part of its nitrogen from the 
air and part of its mineral food from the deep subsoil, 
and leaves the soil in excellent condition to grow potatoes. 
Its use is gradually extending in the eastern half of the 
United States as the methods necessary for its growth 
become better understood. It may never attain to the 
commanding position here which it holds in the agricul- 
ture of the western half of the country, but it is certain 
to become more generally grown than now. An objec- 
tion to the use of alfalfa in a potato rotation in the East 
is that the heavy liming generally necessary induces scab 
on the potatoes. 

The hay crops usually grown in rotation with potatoes 
in the northern states are the clovers, timothy and red- 
top. Except for growing only one season, red clover has 
most of the good qualities of alfalfa. The growth of 
either is a sign of land in good condition. Both require 
considerable lime in the soil, though clover needs less 
than alfalfa. While the potato will make fair crops on 
land that is sour and low in organic matter, it grows 
better if the soil is in the Avell-drained and slightly alkaline 
condition in which the beneficial soil bacteria live best. 
The second cutting of common red clover is often turned 
under in potato rotations on account of benefit to the soil. 
Mammoth red clover is a larger and coarser variety of 
the red. Alsike clover is lighter in yield than the red, but 
is able to grow on many poor, wet or sour soils where red 
clover will fail. It should be substituted for the red 
wholly or in part wherever there is danger that the red 
will fail to grow. Timothy is a hay plant of great value 



Climate, Soils and Rotation 111 

when handled correctly. It will grow on many soils, fur- 
nishes a fairly heavy root system and stubble to keep up 
soil organic matter, gives a good yield of hay which is 
easily cured and finds ready sale at good prices for horse 
feeding. The close sod formed by timothy prevents 
erosion and helps to keep weeds down. The use of lime, 
manure and fertilizers on timothy greatly increases the 
yield and keeps it longer at a high production. A very 
common fault in the handling of timothy is to let it stand 
so long that many plants die out and when the remainder 
are turned under there is but little organic matter to 
supply succeeding crops. It should be plowed while 
there is yet material to enrich the soil. Redtop is a hay 
plant seldom appreciated outside of New England. A 
prejudice against redtop in mixture in market hay re- 
duces the price on account of a common practice of letting 
it stand until woody before cutting. Properly handled, 
its value for feeding is practically that of timothy. By 
the well-known principle that a mixture of grasses yields 
better than either alone, redtop increases the yield of 
mixtures in which it is included and is particularly valu- 
able for humus production on account of its very heavy 
sod. It grows in soils too poor, wet or dry for timothy. 

The selection of the hay plants to be grown in any rota- 
tion with potatoes should be carefully considered with 
the idea of building up soil fertility as well as producing 
hay for feeding or sale. Alfalfa, red clover, alsike clover, 
timothy and redtop require for their growth soils varying 
in fertility, drainage and lime content in about the order 
named. Potatoes should be rotated with alfalfa where it 
succeeds. In all others, and this includes nearly all the 
northern and eastern states from the Red River to Maine, 
the capacity of the soil determines whether red clover 



112 The Potato 

should be sown alone, or another mixture. This might 
be red and alsike clover, the clovers with timothy or both 
timothy and redtop, or perhaps on some of the poorer 
volusia soils and others of that low grade of fertility, red 
clover is best left out unless limed and only alsike, timothy 
and redtop sown. 

In southern sections there is difficulty in growing the 
northern hay plants mentioned. Reliance must be placed 
on annuals for most of the hay and for cover-crops. 
Crimson clover, wheat, rye, winter oats, hairy vetch, soy- 
beans, cowpeas, peanuts and velvet beans are used in the 
southern states for these purposes. 

In the West where irrigation is practiced, alfalfa is 
used more than any other crop to rotate with potatoes to 
supply organic matter. Field peas are also used. 

REFERENCES 

Agee. Crops and Methods for Soil Improvement. 

Brooks. Agriculture, Vol. I, Soils. 

Fraser. The Potato. 

Grubb and Guilford. The Potato. 

Terry. The A. B. C. of Potato Culture. 

Bui. 87, Bur. PI. Ind., U. S. Dept. Agr. Authority for " Critical 

Period," p. 96. 
Bui. 49, Can. Central Exp. Farms, Effect of Heat on Seed Vitality. 
Buls. 347, 352, 397 N. Y. (Geneva) Exp. Sta., and Bui. 159, Vt. 

Exp. Sta., On Effect of Spraying in Dry Season. 



CHAPTER VI 

MANURES AND FERTILIZERS 

By Daniel Dean 

The supply of plant-food elements present in soils will 
produce potato crops of varying size according to the 
climate, the original natural fertility of the soil-type and 
the degree to which it has been reduced or improved in 
condition since bringing under cultivation. Manures and 
fertilizers are used to add plant-food in forms so easily and 
quickly available that the crop will be able to take up 
and use more than it could without them. On account 
of its tender nature, compared with other farm crops, the 
potato responds well to the use of fertilizers. Manures 
and fertilizers are used wherever the increased yield brings 
enough in the market returns to meet the additional cost 
and leave a profit. For these reasons, the use of fertilizers 
is more or less localized in the particular sections where 
their use is most profitable. For example, the cool and 
moist climate of the Aroostook region of Maine is very fa- 
vorable to the production of large yields of potatoes to the 
acre. In spite of the great natural fertility of the soils, 
these fertilizers are used to the extent of over 1900 pounds 
to the acre on the average at a cost of over $30, because 
the practice pays. The great trucking region which 
supplies city markets from April till autumn and extends 
along the Atlantic coast from Florida to Long Island is 
nearly all made up of sandy soils of low natural fertility, 
i 113 



114 The Potato 

The comparatively high prices received for this early crop 
makes heavy fertilizing, often over 2000 pounds to the 
acre, profitable. By contrast, the irrigated sections of 
the Rocky Mountain region often have soils very rich in 
the mineral plant-food elements. Though often low in the 
supply of nitrogen, this is obtained by rotating the potato 
crop with alfalfa. This would render fertilizers of little 
value for these conditions even if the high freight costs 
from our present sources of supply did not put fertilizers 
out of the question. 

Scientists are not fully agreed as to the functions of the 
different elements in the soil used by plants. Experiments 
have proved that several must be present or plants will 
not grow. The common term "plant-food" is applied 
from these experiments. Fertilizers have other actions 
of value to plants, some well understood, and some which 
have only been discovered and are as yet not very well 
known. One is their favorable action on the beneficial 
bacteria present in the soil. 1 Certain fertilizers, by ren- 
dering soil conditions more favorable for them, increase 
indirectly the fertility of the soil as well as by their direct 
action. Our knowledge of these bacteria is limited at 
present in some directions, but it is certain that their 
importance to agriculture is very great, much greater than 
is generally known. One limit to the yield of farm crops 
is the amount of water which is available for their use. 
This is shown by the great gains from the practice of irri- 
gation. Fertilizers practically increase the water supply 
by increasing the concentration of the solution of plant- 
foods in the soil water and so enable the plants to secure 
more from the same amount of water in the soil. 2 

1 Office of Expt. Sta., Bui. 194. 

2 U. S. D. A., Bureau of Soils, Bui. 22. 



Manures and Fertilizers 115 

It is thought that to some extent fertilizers act as disin- 
fectants to reduce damage by unfavorable agents in the soil. 

FERTILIZER PRACTICES 

Elements often present in the soil in too small quantities 
for the best growth are nitrogen, phosphorus, potassium 
and calcium. When these are added in the form of fer- 
tilizers or manure, the yield of most crops is increased. 
The extent to which farmers may use fertilizers depends 
on the cost of the fertilizer compared with the net value of 
the increase in the crop. Another factor which must be 
considered is the residual effect of fertilizers on the soil. 
In the early days of the use of fertilizers, small applications 
were often made without much attempt to maintain the 
soil supply of organic matter. When the amount supplied 
was sufficient only to give the young plant a better start, 
it is probable that the increase in yield removed more of 
the plant-food elements than was added in the fertilizers. 
Being usually applied to grain or to tilled crops, there 
was but little increase in the amount of organic matter 
returned to the soil in the plant residues, not enough to 
replace that destroyed by the processes of tillage. This 
has led to a strong belief among older farmers that " fer- 
tilizers will run out the soil." The present tendency 
among potato-growers is to use much larger applications, 
which supply an excess of soluble plant-food elements 
over those removed in the crop. 

Practice in the use of fertilizers was for many years 
based on the theories of the famous German chemist Von 
Liebig. He taught that plant-food must be returned to 
any soil to equal exactly that removed in the crop. The 
practical error in the assumption that the composition 



116 The Potato 

of a fertilizer for any crop is determined by the chemical 
analysis of the crop itself is that it does not sufficiently 
take into account the great natural stores of plant-food 
in the soil, nor the biological conditions. The plant-food 
needs of the growing plant at any time are not necessarily 
based on its final composition. The presence of a par- 
ticular number of pounds of an element in soluble form 
somewhere among the millions of pounds of soil on an 
acre is no guarantee that the plant roots will be able to 
find and use it at the time when it is most needed. 

Growers in specialized potato-growing regions like Aroos- 
took County and the early truck potato section apply more 
plant-food than the potato can be expected to remove in 
the crop, in order to make certain that it will not have to 
suffer for a lack at any time. The effect of this practice 
is seen in the subsequent crops. In southern trucking 
regions, the choice of the crop to follow heavily fertilized 
potatoes is largely governed by its ability to make good 
use of the fertilizer left by the potatoes. The longer ex- 
perience of European farmers with fertilizers has resulted 
in England in laws by which the value of the fertilizers left 
in a soil by crops is computed. Under the tenant system, 
by which most of the farms of England are worked, an 
outgoing tenant must be paid by his successor for the 
unused fertilizer left. This proportion of the value of the 
fertilizers applied varies with different materials, being 
lowest with the soluble nitrate of soda and highest with 
such slowly acting materials as ground bone and lime. 

MAKKET FORMS OF FERTILIZERS 

Commercial fertilizers are found on the market in the 
form of many different materials which are also manu- 



Manures and Fertilizers 117 

factured into many brands of mixed fertilizers, usually 
being prepared for some special crop or soil. Both the 
materials and mixed fertilizers are sold under statement 
of definite percentages of the plant-foods they contain. 
Annual state inspection and analysis show that these 
statements are usually reliable. Each has advantages 
for farmers' use. The mixed factory goods are usually 
in good mechanical condition for sowing and are generally 
kept or can be soon obtained from dealers. These dealers 
usually extend credit to buyers. The manufacturers 
contend that by the wet or acid process they are liable to 
utilize materials too insoluble for use directly by crops. 
The many trade brands for the same crop may differ 
greatly in composition; and often a number of brands 
having the same analysis are sold as "special fertilizers" 
for widely varying crops. 

The variation between soils is so great that the same 
crop raised on different lands may require widely varying 
fertilizers for the best results. Only experience and careful 
study will show what these requirements are. Such study 
and observation are rather rare in America. In Europe, 
farmers are more accustomed carefully to mix their ferti- 
lizers according to the special needs of each combination of 
soil and crop. In Germany this goes so far that the mate- 
rials are often applied separately at the most favorable time 
for the action of each, although this would not be advisable 
here on account of greater cost of labor. The materials 
used by farmers in home mixtures are usually of high grade. 
Sometimes, as with nitrate of soda, acid phosphate and muri- 
ate of potash, a mixture that is of the right analysis for a 
particular crop may be composed of materials that are 
sticky in combination and do not drill well. Care must 
often be taken to include materials like dried blood, tank- 



118 The Potato 

age, ground bone and sulphate of ammonia that drill well. 
The cost of home mixing may be one dollar a ton, more or 
less, sometimes under fifty cents. A tight wagon box or 
barn floor, screen, measure and shovel are the only belong- 
ings needed if enough is mixed so that batches are made 
up of one or more bags of each material. If less, scales 
are needed. Dealers do not like to sell materials in small 
quantities, but by clubbing together farmers can buy car- 
load lots. 

Most of the phosphoric acid in factory-mixed fertilizers 
comes from acid phosphate. The value is the same from 
any source if acid treated. If not so treated, as in tankage 
or ground bone, it is slower to become available. Most of 
the potash comes from muriate and kainit, which differ but 
little in their action ; some comes from sulphate. Fertil- 
izers vary mostly in the value of the nitrogen. The higher- 
grade factory-mixed fertilizers are more certain to have 
high-grade nitrogen than the low-grade cheaper mixtures. 

Before the great European war, the prices of fertilizers 
had remained fairly constant for a number of years. The 
experiment stations in the northeastern states usually 
value the best grades of nitrogen at 15 to 18 cents a pound, 
soluble phosphoric acid in acid phosphate and potash in 
muriate at about 5 cents. These prices are ton lots of 
the best materials bought for cash in large markets. 
Buyers of car-lots usually purchase enough cheaper to 
cover the cost of freight to country points at these prices. 

Lack of knowledge of fertilizers among farmers has led 
to a failure to appreciate the fact that it is the cost a pound 
of the plant-food which the fertilizer contains and its 
quality that determines the actual value of any fertilizer, 
not the price a ton. Many farmers look too often at 
the cheapest, regardless of the analysis. For example, 



Manures and Fertilizers 119 

muriate of potash contains four times as much potash 
in a ton as kainit and often costs less for the one ton than 
for four tons of the less concentrated material, making 
the potash cost less a pound, in addition to the saving 
in labor of hauling and applying. The cost a pound of 
nitrogen in high-grade dried blood, nitrate of soda and 
sulphate of ammonia at $50 to $70 a ton, may be less than 
in the cheaper grades of tankage and the like, besides 
being of far better quality. 

There is less variation in the price a ton of acid phos- 
phates because the best sold in America seldom exceeds 
16 per cent. The relative cheapness of plant-food in 
mixed fertilizers depends largely on the analysis. 

Mixtures of acid phosphate and potash are compara- 
tively low priced and at the same time are of high grade 
and cheap for the amount of plant-food which they con- 
tain. Nitrogen is so expensive that a small percentage 
runs the price up rapidly. Usually the higher grades of 
so-called "complete fertilizers," costing $30 a ton or more, 
are relatively cheaper than lower grades selling around 
$20 a ton. It is usual for the makers of the higher-priced 
complete fertilizers to claim that the nitrogen in them is 
in a variety of forms of varying quickness of solubility, 
thereby becoming gradually available to the crop through 
the growing se'ason. This is something which should be 
considered by farmers in making up their orders for 
material for home mixing. 

NITROGEN 

Nitrogen helps rapidly to increase vegetative growth. 
When nitrogenous fertilizers are extensively used, the 
foliage grows large and rank and has a dark green 



120 The Potato 

color. In extreme cases the foliage may become too loose 
and open and porous in texture, and so render the potato 
plant more liable to the attacks of disease and sun-scald. 
Lack of available nitrogen for the plant is shown by small 
size and light yellow color of the foliage. Commercially, 
nitrogen used in fertilizers comes from a variety of sources 
which vary greatly in value and in the quickness with 
which they become available. Nitrate nitrogen, the form 
to which other forms must be changed in the soil before 
the plants can take it up in the soil solution, is the quickest 
available. Nitrate of soda is the principal commercial 
form. It comes from deposits in Chile, hence the old 
name of "Chile saltpeter." It is so rapidly soluble in 
water that it may sometimes be dissolved and lost to the 
plant if heavy rains fall before the feeding roots have had 
time to form. For this reason, it is either applied after 
planting as a top-dressing or is used for only a part of 
the nitrogen of a mixture, the remainder being in slower 
acting forms. Because of this rapidity of action, nitrate 
of soda is particularly valuable for use in early spring, on 
early potatoes before the soil warms up enough for the 
processes by which the other forms of nitrogen change to 
nitrate. It contains about 15 per cent of nitrogen. Sul- 
phate of ammonia, a by-product of coke and gas manu- 
facture from coal, is next in order of availability. It 
contains the largest percentage of nitrogen of any material 
— 20 per cent. It has good mechanical condition for 
mixing or sowing. One drawback is that its use tends to 
make land sour and that it is not very efficient on sour 
soils. Nitrate of lime and cyanamid are comparatively 
new commodities, being made from the gaseous nitrogen 
of the air by the use of electricity. While not extensively 
used, it is probable that in time they will become very 



Manures and Fertilizers 121 

important sources of nitrogen. Cyanamid is difficult to 
mix well in fertilizers and has other drawbacks. 

Much of the nitrogen of factory-mixed fertilizers comes 
from organic sources. These are slower in their action, 
as the organic forms of nitrogen must be changed first to 
ammonia and then to nitrate before the plants can take 
them up. Warm weather and warm soil are needed for this. 
Dried blood is the best of the organic forms, with tankage, 
fish scrap and cottonseed meal also used in different sec- 
tions. Other more slowly available forms like leather, 
animal bone and horn meal are nearly useless to the 
potato crop unless treated with acid by the wet process to 
make them more soluble. In comparing the prices of any 
of these materials, the degree of availability must be 
considered as well as the price a pound of the nitrogen. 
It is unfortunate that state laws do not compel the state- 
ment of the percentage of each of the principal forms in 
which nitrogen is found in fertilizers as well as the total. 
At present the nitrogen in as poor a material as dried peat, 
often used as a drier in mixed fertilizers, counts as high in 
the total percentage of nitrogen as from nitrate of soda 
or dried blood. 

Nitrogen is so much more expensive than the other 
elements of plant-food and so easily lost from the soil that 
every effort should be made to conserve and increase the 
soil supply by the use of rotations which provide plenty of 
organic matter, including legumes, and by making soil 
conditions as favorable as possible for the different soil 
bacteria which take or change nitrogen. The other plant- 
foods are in the soil in stable forms which are not easily 
lost. Nitrogen exists largely in very unstable forms which 
are easily lost in drainage water or by changing into the 
gaseous form of nitrogen. 



122 The Potato 



PHOSPHORUS 



Phosphorus, usually referred to under the name of its 
form as phosphoric acid, or P 2 5 , is often in very small 
quantities in American soils, even in those abundantly 
supplied with other elements of plant-food. 1 Its actions 
on growth are not fully understood, but are very im- 
portant and are becoming more and more appreciated. 
A deficiency in soluble phosphoric acid quickly reduces a 
crop yield. Unless a sufficient amount is present, plants 
do not mature properly. Its use tends to produce early 
maturity and is marked by dark green foliage. 

The principal supply for use in fertilizers comes from 
deposits in the South which are supposed to be derived 
from fossil bones. When ground finely, this material is 
sold under the name of "floats" or "raw rock phosphate." 
It is much used in the corn belt states and gives good 
results there on general farm crops. It is too slow- 
acting for the more delicate potato crop, and has not given 
very good results in most experiments in the colder north- 
eastern states. Acid phosphate is made by treating this 
raw rock phosphate with sulphuric acid. This unites with 
part of the lime in natural combinations with phosphoric 
acid. Instead of the insoluble phosphate in which three 
parts of lime are united to each part of phosphoric acid, 
there is formed the water-soluble form in which only one 
part of phosphoric acid is united to each part of lime, to- 
gether with a small proportion of the reverted form soluble 
in weak soil acids in which two parts of lime are united 
to each part of phosphoric acid. The sum of these makes 
up the available P2O5. Acid phosphate is also made from 
animal bones, but the supply is only enough for a small 

1 See Bulletins by Hopkins, 111. Agri. Expt. Sta. 



Manures and Fertilizers 123 

fraction of all that is used. Acid phosphate is the prin- 
cipal source of phosphoric acid in this country, either for 
factory-mixed fertilizers or for home mixing. The word 
"acid" has created a foolish prejudice against its use which 
is not warranted by facts. A very small application of 
lime will prevent any chance of the soil becoming sour 
from its use. Ground animal bone and basic slag are 
valuable sources of phosphoric acid for some other crops, 
but are too slow acting for the tender potato. Different 
grades of American acid phosphates vary in the percent- 
age of phosphoric acid from 12 per cent to 16 per cent or 
more. Only the highest grades should usually be bought. 
The price a pound of the phosphoric acid applied to the 
land is the real cost. 

In the northern states the price a pound at the rail- 
road station is usually less in the higher than in the lower 
grades and in addition there is the cost of hauling to the 
farm and applying to the land. Three tons of 16 per cent 
acid phosphate usually cost less than four tons of the 
12 per cent and the cost of hauling and sowing the extra 
ton is saved. 

potassium 

Potassium, usually referred to as "potash" or K2O, is 
present in large quantities in most American soils. Some 
of the very sandy soils near the seacoast and the swamp 
mucks are likely to be deficient in it. Potash helps in the 
translocation of starch within the potato plant and tends 
to lengthen the life of the crop. Practically all the com- 
mercial supply of potash comes from deposits in Germany, 
controlled by a syndicate there. The principal form used 
in America is that of muriate of potash containing 47 to 50 
per cent of actual potash. This is usually the cheapest 



124 The Potato 

form in which to buy potash. The chlorine in the com- 
bination wjth the potash has some tendency to make soils 
sour, and in some experiments l has produced smaller yields 
and poorer quality than when sulphate of potash was used. 
The latter, 47 to 49 per cent potash, is more expensive and 
is but little used except for tobacco fertilizers. Kainit is a 
raw material of low grade (12 per cent potash), anol is rela- 
tively higher in price a pound of potash contained in most 
places on account of the freight on material of less value. 
Potash fertilizers are mixed in the soil after applications 
and are not likely to be lost by leaching. The solutions in 
soil water are rather caustic, and heavy applications are 
likely to burn the roots of plants if applied close to the 
seed. The old idea of mixing fertilizers according to the 
chemical composition of the crop has led to the use of 
fertilizers containing much more potash than practical 
experience of farmers and scientific experiments warrants. 
Mixed fertilizers often contain 7 to 12 per cent of potash. 
A number of experiments by the Geneva and other agri- 
cultural experiment stations have shown that this is too 
high for profit. Five per cent is usually all that will pay. 
Potash is so abundant in most American soils that nitro- 
gen and phosphorus are likely to be much more needed. 

calcium 

Calcium, in the form of lime, is seldom so deficient in 
American soils as to render its use directly necessary as a 
fertilizer for potatoes. In fact, very heavy yields of pota- 
toes are often grown on soils too acid to grow clover. The 
potato seems to be very tolerant of acid conditions. Heavy 
applications of lime produce conditions under which the 

1 Brooks, Mass. Expt. Sta. 



Manures and Fertilizers 125 

common scab is likely to injure the tubers. 1 The 
powdery scab prefers acid soils and is reduced by liming. 
There are other reasons which make the use of lime of 
great value. The other crops of a potato rotation are 
more likely to be benefited than the potato, and the net 
profit of the rotation as a whole must be considered. The 
clover and grass crops are the ones most benefited by lim- 
ing, and these are the ones that do most to maintain the 
soil supply of organic matter. Heavy sods and other 
residues from hay crops bring up soil fertility rapidly at 
small cost. In this way subsequent crops of potatoes are 
benefited. Lime is also essential for the action of the 
beneficial soil bacteria. Many American soils are now 
becoming deficient in lime. Lime should be added to soils 
in rotation in which potatoes are grown to as large an 
amount as the soil can use without producing scab on the 
tubers. What this amount will be can be found only by 
careful trial on every soil and sometimes on every field. 
Some soils can use several tons of limestone to the acre 
without danger, while 500 pounds might be too much on 
limestone soils or those in high condition of fertility. 
Burned lime has been almost the only source of lime for 
many years. Ground limestone is now coming into use 
very rapidly, and it is probable that before many years will 
entirely displace burned lime in most places. It is much 
easier to apply and its use is safer. Burned lime is thought 
by some to have a tendency to use up the organic matter 
in the soil, even when thoroughly slaked before application. 
Hydrated lime is too expensive to compare with the 
others. Any form of lime should be applied to the crop 
in the rotation which follows potatoes, and should be 
thoroughly harrowed into the soil. 

1 Vt. Bui. 184. 



126 The Potato 

SULPHUR 

Sulphur is present in all soils and is not likely to be 
deficient in any way. There is some ground for the belief 
that part of the value of acid phosphate is due to the 
sulphur contained in it. 

APPLYING FERTILIZERS 

The method by which fertilizers are applied to a soil 
often determines the profit to be obtained from their use. 
Nitrate of soda is so quickly and easily soluble in the soil- 
water that it can be sown on the surface of the land at any 
time with the certainty that the first rain will dissolve it, 
or that it will quickly dissolve if mixed with the soil. 
Other fertilizers require weeks, months or even years to 
become available to plants. 

A gradual evolution is taking place in the ideas as to 
the proper use of fertilizers. In the earlier days of their 
use, when the quantity applied was limited to perhaps 
100 to 200 pounds to the acre, it was rightly considered as 
only a starter for the young plants. It was applied to the 
soil close to the seed, being often dropped by hand. The 
roots starting from the young plants were certain to find 
a supply of readily available plant-food as soon as they 
could use it. This would give a quick start to the young 
plant, which would enable it to grow more quickly to a 
size when it would be able to forage for itself. As the 
profits from the use of fertilizers became known, the 
amounts gradually increased. About the same time 
machine-planters came into use. These applied the 
fertilizer in the form of a strip several inches wide in the 
bottom of the furrow-mark. This wide-strip application 



Manures and Fertilizers Y17 

is essential to prevent root injury. Application with the 
planter works well whenever moisture is abundant in 
the soil throughout the growing season in Maine. As the 
amount applied to the acre increased to 1000 pounds or 
more, growers began to use a wider distribution through 
the soil. With such large amounts, there is no need of 
specially placing some of it near the plants, as a fraction 
is enough to act as a starter. 

At the present time heavy applications of fertilizer are 
used in the specialized potato-growing districts in this 
country, with the idea of supplying so much that the grow- 
ing plant will never suffer for lack of plant-food at any 
time. For such amounts as 1000 to 3000 pounds to the 
acre, broadcasting is coming into use in whole or in part. 
Ordinary grain-drills or special broadcast fertilizer sowers 
are used. All fertilizers broadcasted should be thoroughly 
worked into the soil. While there is some tendency for 
soluble fertilizer salts to work downward into the soil, 
there is likely to come any summer, after potatoes are 
planted, a hot and dry time when several inches of the top 
soil is very dry. The fertilizer in such a dry soil is prac- 
tically useless to the crop for lack of sufficient water to dis- 
solve it. This is especially true when a surface mulch of 
dry soil is maintained for the purpose of conserving the 
moisture in the earth below. This accounts for some of the 
contradictory results obtained by experimenters on com- 
parisons of the application of fertilizers by the drill and 
broadcast methods. Under the conditions of northern 
Maine, in which the water in the soil is usually abundant, 
part of the heavy fertilizer used is often put on after the 
plants are up, being applied to the ridge and covered with 
soil. It is doubtful whether this method would be a 
success in other regions, even in some other parts of 



128 The Potato 

Maine, 1 unless soil moisture conditions are fairly certain 
to be favorable at the time of the second application. 
Nitrate of soda may be applied at any time, as it is so 
easily dissolved. Success with any method of applying 
fertilizer depends on soil moisture conditions. The correct 
method in one case may be entirely wrong in another. 

The writer has developed, for his own farm conditions, 
a method which has been very successful for applying 
large amounts of fertilizer. The soil is a silt loam of good 
water-holding capacity, further increased by the incorpora- 
tion of large quantities of organic matter. The total rain- 
fall for the whole year averages under 30 inches. Periods 
of dry weather after planting, sometimes extending to 
several weeks, keep the surface soil very dry. In some 
fertilizer experiments, acid phosphate applied as a top- 
dressing after planting did not become dissolved to produce 
much increase in yield. At the same time, when it was 
applied deeper in the soil before planting, a good increase 
resulted. The soil is deep, and potato roots easily pene- 
trate to the depth of several feet. The fertilizer is usually 
1500 to 2000 pounds of a mixture of acid phosphate and 
muriate of potash. 

Part of the fertilizer is sown broadcast in early spring 
on the surface of fall-plowed land, thoroughly disked in to 
the depth of 7 to 8 inches and the field replowed to the 
depth of 10 inches. The remainder of the fertilizer is then 
applied and disked in as before. The essential idea of this 
method is to have a large amount of fertilizer so evenly 
and thoroughly distributed through the soil to the depth 
of 10 inches that the potato roots are drawn out and down 
completely to fill this whole space, rather than to have a 
tendency to remain in the more limited space occupied 

1 Maine Agri. Expt. Sta. Bui. 246. 



Manures and Fertilizers 129 

by the fertilizer when either the drill or the broadcast 
method of sowing is used. Scientific experiments show 
that roots multiply mostly in the soil where the supply 
of plant-food is most abundant. 1 The surface mulch 
of dry soil keeps the lower parts both moist and cool. 
Later the heavy tops shade the ground with the same 
result. This cool lower soil, although itself too dry for 
roots to grow in, is a marked advantage in hot seasons in 
preventing degeneration of the potato as well as in increas- 
ing yield. 2 

This method of applying fertilizers has produced very 
striking results in dry seasons. In periods of extreme 
drought the tops showed but little injury from tip-burn and 
grew continuously. The writer thinks that this success 
is due to the greater moisture supply made available to 
the plants by the wide and deep distribution of the root 
system. This enables the plants to find and utilize the 
water in a larger volume of soil at the time when the 
plants need it most. When the roots are encouraged 
to develop near the surface by broadcasting the fertilizer 
and working it in shallowly, the drying of the upper soil 
layer deprives the plants of the use of much of their root 
system, and may leave them in poorer shape to with- 
stand hard conditions than if the roots had been forced to 
spread out and down earlier to find plant-food. 3 In the 
corn-belt, dry weather in June is recognized as a favorable 
factor for the future success of the corn crop because it 
forces the plants to root deeply, while a wet June would 
result in shallow rooting which would be certain to suffer 
later in the summer. 



1 Storer, " Agriculture." Vol. 1, pp. 297-300. 

2 Neb. Agr. Expt. Sta. Bui. 146 ; and Colo. Agr. Expt. Sta. Bui. 216. 

3 Bureau of Soils, Bui. 22, p. 52. 



130 The Potato 



FARM MANURES 

Farm manures increase the productiveness of the soil 
in four ways : first, by the actual plant-food added to the 
soil; second, by the physical effect of loosening and 
aerating the soil and adding to its moisture-holding ca- 
pacity ; third, by the action of the organic matter of the 
manure in making available to the plants by its decay the 
insoluble plant-food of the soil ; and fourth, by improving 
the soil conditions for the work of the beneficial bacteria. 
Any computation based on the trade value of the plant- 
food may be falsified by the other values being even more 
important. A better way is to consider the results ob- 
tained in farm practice by particular crops through a 
series of years long enough for the residual effect of the 
manure on the soil to be measured. The potato usually 
responds well to the use of manure throughout the humid 
sections, and the increase in yield of a cash crop like the 
potato gives quick returns for the use of the manure. 

There is some danger that common scab will be worse on 
potatoes grown on land heavily manured. This danger 
is reduced by using smaller amounts, by having the 
manure rotted, and by spreading some time before plant- 
ing. Horse manure is thought by some to favor scab 
more than other manures, but this is doubtful. 

Manures are poorly balanced fertilizers. They contain 
relatively much more of nitrogen than of the other 
plant-food elements and are likely to produce plants 
with large growth of tops without corresponding tubers. 
This can be prevented by using with the manure 50 
pounds of acid phosphate to each ton, and in rare 
cases potash may be added also. Coarse and strawy 
manure may make some soils too open and porous, 



Manures and Fertilizers 131 

causing them to dry out, particularly in dry years and 
dry climates. 

A practice in handling manure that is gaining ground is to 
apply it to the hay crop preceding potatoes in the rotation. 
By increasing the yield of the hay, the organic matter left 
in the soil by the roots, stubble and aftermath is increased 
for the use of the potatoes later. When manure is applied 
directly to the potato crop, it is better spread in the pre- 
vious fall or winter than just before plowing. The manure- 
spreader does better work than hand-spreading because of 
the practical impossibility of getting as even distribution 
with a fork as with the machine. Unless the potato- 
grower has only a small area, it is more profitable to give 
the whole a thin coat of manure than to have parts heavily 
covered and the remainder without any. Experiments 
extending over many years show that the profit to a ton 
decreases as the size of the application increases. The 
manure-spreader has an advantage over hand-spreading 
in this respect because smaller amounts to the acre can be 
spread evenly. 

The value of farm manure is greatly reduced by poor 
methods of handling. The best net returns from its use 
come from spreading as soon as possible after it is made. 
When necessary to keep it for some time, as when fields 
are occupied by growing crops in summer, precautions 
should be taken to prevent loss. Exposure to rains may 
leach away half the value in a short time. By heating in 
piles, much of the nitrogen escapes. Keeping under cover 
prevents leaching. Keeping in shallow piles, tramping by 
animals and occasional wetting prevents heating. Land 
plaster and other substances are mixed with the manure 
to prevent the loss of nitrogen. Raw rock phosphate 
or " floats " is valuable for this purpose in addition to 



132 The Potato 

its phosphoric acid, the element needed to balance the 
manure as a potato fertilizer. Acid phosphate is valu- 
able for this purpose, but it must not be used under the 
feet of animals. Manure spread in the winter suffers no 
loss from heating and but little from leaching unless the 
field is so sloping that water runs off rapidly. It is so 
difficult to prevent loss in manure kept in other ways 
that spreading as rapidly as made is the best method in 
most cases. 



REFERENCE 

Voelcker and Hall. The Valuation of Unexhausted Manures. 



CHAPTER VII 

PLANTING 
By Daniel Dean 

Soil preparation for planting potatoes should be such 
as will meet the peculiar demands of the potato plants. 
A loose and mellow soil is needed for extension of the weak 
and tender roots and for the development of the tubers. 
Preparation should be designed to correct the faults 
of the local soil and climate as far as that can be accom- 
plished. Preparation before planting should be such as 
will reduce the tillage after planting as much as possible. 
Weeds are more cheaply killed by wide-spreading tools, 
like harrows and disks, than by small, single-row tools 
or by hand hoeing later. 

Fall plowing is of great value in all but the lighter 
soils. It rots the soil organic matter, puts the land into 
better physical condition by exposing the bare soil to 
winter freezing, stores up more water for the use of the 
crop and sprouts and kills part of the weed seeds in the 
ground. The control of insects, like the white grub 
and wire-worm, is easier with fall plowing because the 
larvae are more exposed to freezing and to attacks of 
their natural enemies, such as birds. As a rule, the 
heavier a soil, the more it is benefited by fall plowing. 
There is some saving in labor by fall plowing in the 
northern states because potatoes are usually followed 

133 



134 The Potato 

by spring-sown grain, which requires considerable work 
early in the spring. The harrowing needed to place 
fall-plowed land in condition for planting takes less 
time than spring plowing and the harrowing necessary 
to cut up the sod well. Harrowing must be deep and 
thorough or the benefit of fall-plowing may be largely 
lost. While there is some additional loss of moisture 
from plowing a second time in spring, this later plowing 
greatly reduces the amount of harrowing necessary and 
makes certain that the soil is well pulverized to the 
depth of the furrow. It is well to fall-plow land as 
roughly as possible with the furrow-slice standing nearly 
on edge. A rough surface catches the rains better, ex- 
poses the soil better to the action of frosts and reduces 
the damage by winds through the winter. Water is 
saved in fall-plowed soil because the layer of sod or 
trash at the bottom of the furrow prevents the water 
in the subsoil from escaping as readily. Straw or manure 
spread on the surface before fall plowing will usually 
become rotted enough by spring to give little trouble if 
replowed. The mellow soil with rotting organic matter 
holds more water than unplowed land would, especially 
in places like dry knolls. Clover sods rot quickly, but 
sods of the grasses take longer. With spring plowing 
only, it is beneficial to cut up the grass sods with a disk 
harrow before plowing. The sod rots more quickly and 
the soil settles together better so that the movement of 
the water in the soil is not hindered. 

Earliness is a great advantage in spring plowing in the 
northern states. An experiment by King at Wisconsin 
showed that water equal to If inches of rainfall was 
evaporated in one week in spring. Water evaporates 
from the soil very fast in the first days of spring after 



Planting 135 

the frost goes out. This water can seldom be fully 
replaced by later rains. Its conservation may often 
turn the scale between success and failure in droughts 
late in the season. Fall plowing has here an advantage 
over spring plowing because it is possible to cover many 
acres with harrow or disk in a few days as soon as the 
ground can be worked without injury in the spring. 
By going over fall-plowed potato ground once before 
sowing spring grain, the saving in moisture for the potato 
crop will more than pay for any loss of grain by slightly 
delayed sowing. 

TILLAGE TOOLS 

The plow is the standard implement of tillage. Ex- 
cept in special cases, nothing has been found to equal 
its work. The common plows used in the East and 
South are drawn by one, two or three horses or mules. 
The two-bottom reversible sulky plow is coming much 
into use in the East. It is heavier and more expensive 
than the common plow, but will work better in soils of 
varying hardness, and in plowing alfalfa sod. This 
reversible sulky plow, like the ordinary two-bottom gang 
sulky used in the central West, does poorer work in plow- 
ing under straw, stalks and the like than the ordinary 
walking plow. The plow can turn under sods, and so 
forth, more perfectly than any other tool, and its use 
distributes surface organic matter. The jointer enables 
sod and trash to be buried more completely. 

The type of harrow to be used depends upon the work 
to be done. Harrows may be used merely to fine and 
smooth a rough surface, like the spike-tooth harrow, or 
may be designed to tear up and fine the soil to consider- 
able depth, like the disk and spring-tooth types. The 



136 The Potato 

disk and its variation, the cutaway, are used most in 
soils nearly or quite free from stone. With these the 
soil can be thoroughly fined nearly to the depth of the 
plowed furrow. The disk will cut up sods or straw and 
will work in soils so full of weed-roots that other types 
of harrows will be clogged. The spring-tooth harrow is 
used more than the disk in sections with stony soils. It 
pays to keep the cutting edges of the disk or the points 
of the teeth sharp. The spike-tooth smoothing harrow 
should follow the disk to level the surface before plant- 
ing. It is also valuable to keep a surface mulch before 
planting and to kill weed seeds that have sprouted. 

The roller is a tool of great value, but is often used 
with poor judgment in potato-growing, because it has 
considerable weight for the small surface. Its action, 
resting on the soil, is to firm the earth to a considerable 
depth, something seldom necessary with potatoes unless 
on very light soil, and is often harmful. Used to follow 
the plow after plowing in the spring, it may help to pre- 
vent sods on edge from making open spaces in the soil. 
Too often it is used with the idea that it is necessary, 
as with the grains and grass seeds, to firm soil around 
the seeds to furnish moisture for germination. The 
roller is used to assist the germination of grain and grass 
by packing the soil around them, causing it to become 
damp by the capillary rise of water. Such seeds are 
dry and need water to start, and their small size demands 
closely packed soil for the benefit of the roots. Unlike 
the dry grain seeds, the large potato seed-pieces have all 
the water they need, 80 per cent, and can grow for weeks 
without any from the soil. This fact is familiar to those 
who have seen potatoes in cellars send shoots to the 
length of several feet. Soils are seldom too loose for the 



Planting 137 

potato and are very often too hard. The plank float, 
or clod crusher, is a better tool to crush lumps, and does 
not settle the soil below the surface as does the roller. 
Such lumps crush easiest a few hours after a rain. 

The depth of plowing for the potato should be as great 
as the fertility of the soil will permit. The weak potato 
roots need all the space they can get. Outside of the 
arid regions of the United States, care must be taken 
not to expose much of the cold and infertile subsoil at 
any one plowing. Where it is necessary to plow land 
deeper than formerly, not over one inch of subsoil should 
be turned up at a time. Organic matter must be added 
to lighten the subsoil turned up, as it is very deficient in 
this. Sandy soils, in which potato roots penetrate easily, 
need deep plowing less than heavy soils. Only three to 
five inches is used in some sandy sections. Heavier 
soils, if well provided with humus, are frequently plowed 
to the depth of ten inches or more, usually about 6 or 
7 inches. 

RESULTS OF TILLAGE 

The results of soil tillage are : 

(1) The organic matter in stubble, manure, and the 
like is buried in the soil, to decay there. 

(2) The mineral particles are made finer, and fresh 
surface exposed to the action of solvents, such as soil 
water and carbonic acid. 

(3) The soil organic matter is broken up and easily 
changed into more useful forms. The rapidity with 
which soil organic matter is destroyed by tillage is 
little appreciated. The common saying, that "tillage 
is manure," is practically true. Tillage is expensive in 



138 - " :' - _ : * " " 

iiizrr and eIsc ezpii^ f iz :iir rin-grs :: rrrciic-es :~ 
:jif soil _-_ 5 ; il :z:r::igr-iv "riiiri ::r ?. 7 ::..:: r-rop zz5 



:f die United States potato-growing has gained a bad 
reruTiTirz ::"::; :iit rs,r:-ii~ ~ri: ~r_i::i :: reduces riie 
ferTiliTy :•: :lr soii. In oilers -ir-f rrpxni: — -i~er is 
kept jp by good rotation and where Eertilraas are nsed 

/.t;. ":/" t :oiT:-^:~inp if re^iriei. ?.s a suns —?.' :: 
enriri: trie ~~d A sinpie nilied ;r:r. like po Times :r 
:-:m. r is. res : r s:L in reTTer r-"-"5i:-v- :-:~-n~cn re ;t:~ 



latiei as 



-~- -::":::: : .: : ::n iirxiie mis. in rim sc-ts 



- in 
Teria ::' in 



il are favored by plenty of air in the 9ofl 
.creased jreaTiy in ~ ~~ -^ ana a::i"T7". _niir 
ii:; : :-:r : r : : the soil plant-food. 

Tnri e ~ dere zTrie :r ~: air is nrese" Tiiia^e r— 



" Ullage s~ uses fresh soil surfaces ro the air and at 
drsT ranses sonae i:ss :: misTare Lo: selling Tne 5.:: e 
s:ii ~ Tiiia^e prevents e'.nar-rnaTicn :r:~ cdi i:~er y ;.::? 
of the soil bv breaking up eapiflarv connection between 



Planting 139 

the soil under the tilled area and the surface. Until 
capillary action is again established by the settling to 
gether of the tilled soil, but little water ran be lost by 
evaporation. A thin layer onl\ of loose soil is sufficient 
ro prevent evaporation, A thin layer settles together 
s >oner than a thick one and needs breaking more often. 
More emphasis has usually been placed on tillage o( 
potatoes after planting than before planting, 'The 
great soil supply o( water in late winter and early 
spring presents opportunities for conservation that exceed 
those during the growing period of the crop, In recent 
years a change has eome about in the attitude of Inves 
tigators towards the value of summer tillage. Extended 
experiments have shown that one Factor which was 
largely neglected by early experimenters is o( impor- 
tance this is the ability of the plant root to sei e 
upon the use of soil moisture. When the soil is not 
occupied by a growing- crop, there is no doubt that a sur- 
Face mulch of loose soil does conserve moisture by pre- 
venting evaporation, but when the soil is well filled with 
plant roots, there is little more water evaporation From 
untitled soil than from tilled, The gains in yields ob- 
served from tillage come from another source weed 
killing — rather than from prevention o( tho evapora 
tion. This means that the Farmer will till practically 
as much as under tho Former practice, but will have in 
mind weed killing as his principal object, instead of pre- 
venting loss o( water. In practice this will mean that the 
tillage of the potato crop during the growth of the crop 
will be done earlier than has been the custom. Water 
will be conserved by fall plowing where possible; by the 
addition of organic matter to the soil ; and by early spring- 
tillage to save the water supply. The soil will not be 



140 The Potato 

allowed to dry out for the late main crop of the northern 
states before planting. All this early tillage also kills 
many weeds which have formerly been left to be killed 
by inter-tillage later on. 

After planting there is a period of several weeks when 
large and wide tools can be used to advantage in tillage. 
The harrow, leveler and weeder cover several planted 
rows at once and kill weeds very cheaply, besides saving 
moisture. 

The necessity of weed killing for the production of 
large crops is even greater than the saving of moisture 
by tillage. Weeds not only rob the potatoes of mois- 
ture, but are able by their stronger root systems and 
greater foraging ability to seize upon and use the soluble 
plant-food in the soil. Very small weeds in this way 
injure the potato crop more than would be supposed. 
The weeds which sprout from seeds in the soil are more 
easily killed before coming up than afterward. The 
tender shoots from the seeds are killed by a light stirring 
of the soil which would not affect them at all a few days 
later. The sprouts starting from the seed have but little 
vitality until they can reach the surface, and produce 
green leaves. Then roots start to secure plant-food which 
is worked by the leaves into material for further growth. 
Every day now adds to the ability of the young weed to 
stand punishment and live. Several successive crops of 
weed seeds can be sprouted and killed by tillage between 
planting and the time when the potato tops are six inches 
high. Tillage at this time can be done carefully enough 
to prevent injury to the growing sprout of the potato 
before it comes up and until it is established for itself 
in the soil. Perennial weeds with root stalks, like quack 
or witch-grass, are much easier controlled by previous 



Planting 141 

cultivation in the fall or early spring than by tillage during 
the life of the potato. The reserve of nourishment in the 
root stalks enables them to stand punishment for several 
weeks and recover from it to injure the potato after 
tillage is no longer possible. 

The preceding results of tillage have all been favorable 
to the potato plant. Tillage has another action which 
has not been sufficiently studied and which has led to 
many conflicting results in experiments and in farmers' 
practice. It is a fact that tillage can injure the potato 
plant even easier than it can the tough and hardy weeds. 
It is very difficult to work with soil near the potatoes 
without injuring them. As the season advances, this 
becomes more dangerous to the potato. While the 
young plant is still attached to the seed piece and draw- 
ing on it for nourishment, it can lose part of its small 
roots without great loss, particularly as the weather is 
yet cool and favorable to the vitality of the crop. Each 
day the potato grows older increases the danger of loss of 
yield from injurious root injury. In the later part of 
the plant's life, the whole upper soil becomes filled with 
roots. These come so close to the surface that it is most 
difficult to work any tillage tool without some injury. 
Few tools except the hand hoe can be worked as shallow 
as one inch, and many of the larger roots are that close 
to the surface. Under some conditions, late tillage may 
do less injury to the potatoes than under others. In 
periods of abundant rainfall, the plants may tend to 
root too close to the surface and some root-pruning may 
force the potato to root deeper. If drought comes later, 
this will be a benefit to the crop. In very cool seasons 
in which the potato does not suffer from extreme heat, 
root-pruning by tillage tools does less damage than in 



142 The Potato 

hot and dry seasons. The loss in yield from tillage at 
the wrong time, too deep, or too close to the plants, 
often amounts to a large percentage of the crop. The 
greatest danger from excessive tillage is likely to come 
in the northern states in which late cultivation of the 
main crop comes at the hottest time of summer. When 
the "critical period" of the plant's life comes at the 
time when climatic conditions are most unfavorable to 
the potato, any injury to the roots is likely greatly to 
reduce the yield. 

PLANTING 

The time of planting depends on the market for which 
the crop is grown and the local soil and climate. The 
higher prices received for extreme earliness in the south- 
ern truck crop compel the use of short-season varieties, 
like the Triumph and Cobbler, and planting very early 
to get the crop on the market before prices fall. All 
cultural methods are arranged with this end in view, so 
there is little choice in the time of planting. Along the 
Canadian border and in much of the Rocky Mountain 
section the whole growing season is but little longer than 
the life of main-crop varieties. But in most of the prin- 
cipal growing states, from New England to Iowa and 
Nebraska, it is possible to vary the time of planting 
by several weeks. Here, as a rule, most potatoes are 
now planted in late May and in June. The later plant- 
ings yield better because the crop matures in cooler 
weather than with early planting. Moisture is more 
likely to be abundant in fall than in late summer. The 
dangers of late planting are late-blight and rot, — unless 
spraying with bordeaux is practiced, — injury from early 
frost and earlv fall freezing of the soil, and conflict of 



Planting ■ 143 

the later tillage of the crop with the rush period of 
haying and harvesting. But increasing competition of 
the southern crop is forcing many growers to abandon the 
previously profitable early crop for local trade. Bordeaux 
spraying has been found to lengthen the life of the potato, 
and potatoes to be sprayed may be planted slightly earlier 
than those unsprayed, for that reason. 

The methods of ridging and level culture with deep 
and shallow planting are best illustrated by their use in 
two of the best-known potato-growing regions of the 
United States. Ridge culture with comparative shallow 
planting is used in Maine. The northern latitude of 
Maine makes the growing season short compared with 
the southern states. The mean temperature of the 
month of July is only 62° to 65° F. Frosts are frequent 
in June and September and may occur in August. Not 
much field work can be done before the month of May, 
and October 10th is regarded as the danger line beyond 
which potatoes are likely to be frozen in the ground. 
Only a short distance away in the Atlantic Ocean, the 
cold ocean current from the Arctic reaches the warm Gulf 
Stream. The fogs of the fishing banks here are well 
known. The rainfall is heavy and is seldom deficient 
throughout the growing season. The rainfall of winter 
is largely available to the potato crop. The ground is 
covered with snow all winter and the loss by run-off and 
evaporation before time of planting is much less than 
that of the other great producing states. The soil con- 
ditions of Aroostook County, the great potato-producing 
section of Maine, are favorable for the retention of soil 
water. Most of that section has been cleared from the 
forests only a few years, compared with the longer settled 
communities, and the soil is well supplied with organic 



144 The Potato 

matter. The region is so damp that the higher and 
dryer parts are usually considered safer and better for 
potatoes than those lying lower. The more or less 
gravelly limestone loam soil crumbles easily and seldom 
gives trouble by baking. With such conditions under 
which surplus of water is more to be feared than a de- 
ficiency, Maine growers use an extreme ridge culture. 
Instead of leveling down the ridges left by the planter and 
depending mainly on the use of leveling tools and the 
weeder to kill the weeds sprouting among the plants in 
the row, Maine growers kill the weeds in the row by 
ridging several times. There is little danger that the 
growing plants in the ridges will suffer from lack of 
moisture. Ridge culture is also the favorite in the ad- 
joining provinces of Canada, in which conditions are 
similar. This culture is suited to wet climates and 
wet seasons. Digging is rendered easier by ridging 
where the soil is likely to be wet. The first ridging after 
the plants come through the ground covers the small 
plants and prevents injury from late frosts. In many 
other sections, such covering would result in baking 
the soil. Ridging is necessary under the methods of 
irrigation in order to prevent injury to the potato plants 
from the irrigating water. 

Long Island potato-growing stands as an example of 
prosperous farming, where a different method than the 
ordinary is used. The soil of Long Island is a rather 
light sand which is easily tilled and dries out quickly 
after rain. Level culture is used because much better 
yields are secured than by ridging. Less soil surface is 
exposed to evaporate water by level culture. 

Partly owing to the high prices in late summer, Long 
Island potatoes are planted as early in the spring as the 



Planting 145 

ground can be worked — last of March and April — 
and mature in the dry weather in July and August. 
Deep planting and level culture exposes less of the easily 
heated sandy soil to the sun and reduces danger of heat 
injury as well as that from drouth. The light soil usually 
is dry at digging time, gives little trouble in digging, 
though sometimes fields left late before digging are 
ridged to kill weeds which have started. Level culture 
is a relative term as some earth is thrown toward the 
plants by the teeth of the cultivators. This prevents 
the growing tubers from being sunburned. Deep plant- 
ing allows the soil over the rows to be thoroughly worked 
in the week subsequent to planting. Weeds are easily 
killed at this time and soil water conserved for the later 
use of the crop. As a rule, early planted potatoes should 
be put in shallower than late potatoes, as the sprouts 
start more slowly in the cooler soil. Very shallow plant- 
ing is seldom advisable unless the soil is so wet and cold 
that heavy ridging is necessary for drainage. Growers 
in other sections of the country use methods between 
the two extremes, according to their conditions. The 
truck crop of the South is raised under soil conditions 
similar to those of Long Island. The need of securing 
warmth in the soil to hasten growth leads to some ridg- 
ing. Shallow soils with hard-pan close to the surface 
as in the volusia soils of New York, Pennsylvania and 
Ohio, present a hard problem. Ridging is the usual 
method used in this section on account of trouble in digging 
in wet seasons, and with the usually stony soil, it is diffi- 
cult to control weeds near the plants by the use of other 
tools than those which ridge the rows. Light and dry 
soils particularly, if likely to be fairly dry at digging 
time, do better with nearly level culture. 



146 The Potato 

The advantages of having sufficient soil over the seed 
to permit wide tillage after planting are so great that it 
pays growers to plant deep enough for this purpose. 
The bottom of the furrow made by the planter or marking 
tool should be at least two inches below the level of the 
surface of the soil and better three or four; for sandy 
soil likely to be dry, even more. Growers are often 
deceived at the depth they plant by looking at the depth 
of the mark below the level of the earth thrown out by 
the marking tool instead of taking the measure from the 
true level of the surface soil to the bottom of the furrow. 

Hill and drill planting 

Two principal methods of planting are used in the 
United States. Potatoes are said to be in hills, checks 
or squares when the ground is marked both ways and 
the seed dropped at the intersection of the mark. This 
method is much used for hand planting. It has the 
advantages of permitting cultivation both ways and 
so weeds are easier kept under control. With poor soils 
the large area allowed to each hill is an advantage, as 
each hill has enough space to produce a good yield. Rows 
in the United States are from 30 to 42 inches apart ac- 
cording to the value of the land, the amount of stone in 
the soil and according to the fertility. Unless the ground 
is very poor, it is advisable to have the hills closer to- 
gether in the short way of the field to give a large yield. 
When planted in drills, the seed is planted from less than 
12 inches apart in the row in the best soils, to sometimes 
nearly 2 feet in poor soils. Planting in drills is rapidly 
gaining ground in the United States, as the yield from 
the larger number of hills is larger to the acre than when 



Planting 147 

planted in hills. Growers in all the important potato- 
growing sections find it practicable, by modern tillage 
methods, to keep weeds subdued in drills as well as in 
hills. The prices received for potatoes from sections in 
which drill culture is general are higher than from those 
where hill culture is mainly used. City markets demand 
medium-sized tubers, and pay better prices than for the 
coarse and overgrown ■ tubers raised in hills. When 
machine diggers are used, digging costs the same when 
either method of planting is employed. With hand 
digging, the larger number of hills to the acre under drill 
culture takes more time to dig than with hills and may 
reduce the acreage by limiting the amount which can be 
dug before freezing weather. The constant improvement 
in the manufacture of diggers is producing machines that 
will dig in very stony soils. 

The general rule for spacing hills is to vary the number 
of hills to the acre according to the yield which may be 
expected. As the distance apart decreases, the weight of 
the individual hills and the size of the tubers is reduced 
and the total yield to the acre is increased. The cost of 
planting and digging may be increased. Digging close- 
planted hills is rather expensive. The smaller size from 
close planting brings higher prices in city markets. An ex- 
treme case of close planting is that in the island of Jersey 
where potatoes are planted 12 by 16 inches, or over 
32,000 hills to the acre. With very rich soil and hand 
tillage, a yield averaging over 400 bushels to the acre is 
secured, even when dug for the early market, while still 
growing. The type of the potato variety affects the 
spacing. The common Rural or Blue Sprout type sets 
fewer tubers to the hill than the Green Mountain or 
White Sprout type and should be planted closer on that 



148 The Potato 

account to prevent coarseness, a common fault complained 
of by city buyers in Rurals. Early types like the Bliss 
Triumph and Irish Cobbler are usually planted closer 
together than late varieties. In Europe it is a common 
practice to use small tubers uncut for seed. These are 
often secured by planting very close, sometimes as little 
as six inches apart in the row. As before noted, wide 
spacing allows faster digging on stony soils. Regions 
of intensive potato-culture, such as Maine, Long Island 
and the coast-trucking region, usually plant rows 30 to 
36 inches apart and the seed dropped 12 to 16 inches 
apart in the rows or 12,000 to 16,000 hills to the acre. 
Regions with stony soils, as the Steuben County and 
Chateaugay sections of New York, plant to some extent 
in checked hills about 3 feet each way or less than 5000 hills 
to the acre. The regions where the expense for rent of 
land, fertilizer and care are high use close planting, while 
low-priced land with other small expenses allows more 
space to each hill, which may be of value in bad seasons. 

Planting tools 

Machine planters of several types are in use and a 
larger proportion of the total crop is planted by machinery 
each year. Hand planting is used mainly in stony and 
rough sections, in the South where the labor is cheap and 
not well adapted to using machinery and to sections 
and farms where potato-growing is of small extent and 
regarded as secondary to other farm crops. Machine 
planters are nearly universal in such regions of intensive 
potato culture as northern Maine and Long Island. 

Machine planters are of two types. In one the seed 
is picked up from a hopper and dropped by revolving 



Planting 149 

pickers ; in the other the seed potatoes are fed on a plat- 
form containing a revolving wheel. An assistant to the 
driver sits behind this and corrects the mistakes of the 
planter by removing the extra pieces where two or more 
are fed between pairs of spokes and by filling the spaces 
which are empty. The first requires only a driver, an 
advantage where labor is scarce. The picker type does 
fair work where the seed planted is small and round, 
and on smooth land. Its efficiency falls off with the use 
of cut seed and on rough or stony land. The picker may 
injure the seed and spread disease. Picker planters are 
most used where land is cheap and labor high, where 
cheap cull seed is used with mellow soil and in general 
where it is the object to raise large areas at low expense. 
The platform type planter is adapted to higher priced 
land where every missed hill is expensive. It will feed 
cut seed perfectly with much less trouble to the feeder 
if care is taken to cut the pieces somewhat blocky in 
shape. With expensive seed and when spraying, manure 
and fertilizer add to the acre cost, it does not pay to 
have any missed hills to cut down the income from each 
acre. The cost of each acre is the same whether every 
hill is planted or not and the cost of the wages of the 
second man on the planter is small compared with the 
increased income. 

The use of machine planters has called attention to 
several advantages in their use which may be copied 
with profit by growers planting by hand. The saving in 
cost of labor over hand planting may or may not be great 
when the cost of the machine is considered. The gain 
from the use of machine planters is largely in other ways. 
The machine opens the soil with a small plow or disk 
and the seed is dropped into soil which is cool and damp. 



150 The Potato 

There is no tendency, as is often the case with hand 
planting, for the seed to become dried out before cover- 
ing. In some sections as on Long Island there is trouble 
with seed slightly infected with late-blight germs rotting 
in the ground after planting. Trouble of this kind is 
much worse where furrows are left open and the soil 
warmed to a temperature at which the blight germs 
develop and rot the seed. Seed which becomes dried out 
before or after planting seldom produces as good a yield 
as where it is allowed to keep all its moisture. The seed 
planted with the machine planter is put in to a more uni- 
form depth than seed in rows dropped by hand which falls 
on each side of the center of the row and forces the culti- 
vator teeth to be kept away on account of injury to the 
plants which are set out of line by hand planting. The 
seed dropped by a machine falls in a straight row which 
is less liable to injury from cultivating tools than that 
dropped by hand. The weeds growing next to the plants 
are the ones hardest to kill, and a perfectly straight row 
easily kept clean reduces the damage from weeds. It is 
noticed that in sections where machine planters are in 
common use the rows are usually planted close. The 
soil in the space between the rows is so tramped by horses 
and wheels of tools that it is of less value to the crop 
than that in the row. The yield is increased by a larger 
number of rows to the acre. Planters are often furnished 
with a fertilizer attachment which applies the fertilizer 
along with the seed. The fertilizer should be dropped 
in a strip several inches wide and covered with soil before 
the seed is dropped or the sprouts may be injured by 
the action of the dissolved fertilizer salts. 



Planting 151 

Hand planting 

More potatoes are planted by hand than by machines. 
If well done, hand planting can be made nearly as good 
as machine planting in some respects and far better in 
others. It is scarcely possible to make a row as straight 
and in as perfect a line as with a machine, and in prac- 
tice the seed and soil must be exposed to drying for a 
short time at least. The objection is often made that 
machines cannot be made to plant deep enough. Much 
hand planting is too shallow because the tools used in 
marking the rows do not make the marks deep enough. 
The three or four point markers used in many sections 
cover ground fast, but the marks are very small. In 
light soils these markers can be shod with iron points 
large enough to make a fair mark. In heavier or stony 
soils a small landside plow, or better a wing shovel plow 
such as is often used for ridging should follow the marker 
to deepen the furrows. All marking tools should be run 
with great care to keep the rows straight. Crooked 
rows result in damage to the potato plants by the culti- 
vator teeth later in the season. Opening the furrows 
just ahead of dropping, and covering right after, reduces 
the danger of drying out seed and of warming the soil 
too much. Covering the seed may be done with the hoe 
or with a small plow, with a shovel plow or "middle 
buster" in the South or with a hiller with wings on each 
side of the row. With shallow soils the hand hoe does 
the poorest work, as there is not enough earth placed 
over the seed to allow tillage with harrow, weeder and 
the like. Seed covered with the hoe in deep soils allows 
such tillage to gradually fill up the mark, at the same 
time killing many weeds. It has a great advantage for 



152 The Potato 

early potatoes in heavy soil, as the amount of earth covered 
over the seed is so small that the plants come up much 
quicker in cold springs than where several inches of dirt 
are ridged over the seed. 

SEED POTATOES 

The problem of conserving the full vitality of the seed 
potato until planted is a hard one unless cold storage is 
available. The white sprouts formed in ordinary storage 
cellars rapidly reduce the vitality of the seed, are easily 
broken off and cannot be planted. The potato requires a 
resting stage for some time after maturity, after which it 
starts the sprouts rapidly at temperatures as low as 50° F. 
If the temperature of the storage space can be kept down 
to from 34° to 36°, the sprouts will not start and the whole 
strength of the seed will be saved to grow the crop. Every 
attention should be given in early fall, winter and spring 
to keep the temperature down. Keeping the doors and 
windows open on cool nights and closed daytimes in 
fall and spring and using ice to keep down the heat re- 
duces the sprouting. Potatoes intended for seed in 
cellars sprout less in shallow piles on the floor than when 
piled up too near the ceiling, owing to difference in tem- 
perature. A special cold-storage plant would be ideal 
but is too expensive for farmers unless for very large 
growers. A very good method of storing seed which is 
falling into disuse is that of storing in pits covered with 
alternate layers of straw and earth to prevent freezing. 

A European practice which may in time be adopted in 
America is that of greening seed. The high cost of land 
in Europe, low cost of labor, large proportion of small 
tubers in the varieties grown, vigor of small tubers which 



Planting 153 

makes them safe for use as seed, use of immature seed, 
and trouble with seed germinating, have led to the use 
of a method of care of seed by which it is kept in winter 
and spring in shallow trays racked up in buildings so 
constructed that each tuber is in the light. The sprouts 
at the seed ends start and grow short, green and stubby. 
When planted, these potatoes start quickly and grow 
rapidly. The cost of the equipment and of the labor 
required to place the seed in the racks and again to place 
the seed in the ground with every seed end up, would be 
very heavy in America. Unless seed which has been 
sprouted in this way for some time is planted with the 
sprouts up, there is trouble in loss of stand. A modifica- 
tion of this plan may be used, however, for American 
conditions of cost of labor. Such short green sprouts 
grown in the light for a short time, perhaps two weeks 
or less, will not be broken off in a potato planter and will 
give no trouble about coming up. It is, therefore, prac- 
tical to keep the seed on a barn floor in the sun for that 
time and save the strength of the sprouts which would 
be lost by growth in a cellar. For a few days the seed 
may be left in crates in the sun without making too long 
sprouts in the crates. 

When seed potatoes are disinfected with formaldehyde 
solution for common scab or with corrosive sublimate 
solution for both rhizoctonia and scab, the crates may be 
disinfected at the same time by having a vat of solution 
in which the crates of seed are immersed. Soaking too 
long or in too strong solution injures the vitality of the 
eye. The seed must not be cut before soaking and must 
be dried at once or rot may result. 

The above-mentioned plan is much used in Europe to 
plant tubers from li to 2\ inches in diameter without 



154 The Potato 

cutting. Trouble with soil diseases affecting the stand 
is causing the use of similar small seed in some of the 
western potato-growing sections. The use of small culls 
as seed is usually condemned in the United States. Very 
often the vitality of the cull seed is low on account of 
disease or degeneration in the parent hill. Many experi- 
ments have generally resulted in higher yields from use 
of large seed cut than from small uncut seed. Even if 
the small seed is used on part of the field on account of 
the lower cost, it will pay growers in the northern states to 
have seed plots in which large cut seed is planted. While 
the results of the many experiments of the cutting and 
size of seed are often conflicting some general rules may 
be stated : — 

(1) The yield to the acre increases with the size of the 
seed piece up to 50 or more bushels of seed to the acre 
when the distance of planting is the same. 

(2) The yield to the acre increases with the size of the 
fraction of the seed tuber from one eye up to the whole 
large tuber. 

(3) The net yield to the acre above the amount of seed 
planted and the increased value of seed potatoes kept till 
spring compared with an equal number of bushels on 
increased yield which must yet bear the expense of digging, 
storage and marketing, reduce the size of the most profit- 
able seed to plant to much smaller size. 

(4) Increasing the number of hills to the acre to- 
gether with the amount of seed used, while keeping 
the size of the seed constant, increases the total yield 
and reduces the yield of the individual hill and the size 
of the tubers. 

(5) Cutting the same weight of seed to an acre into 
smaller pieces may or may not increase the yield because 



Planting 155 

the seed will, at some size, be cut too small to insure a 
good start to the plants. 

(6) As noted above, salable tubers used as seed usually 
outyield cull seed, because of the fact that a larger portion 
of the culls come from weak, diseased or degenerate hills. 
The cull is not poor seed because small, but because there 
is a greater chance that its inherited vigor is low. In 
cool and wet climates, like those of Scotland, Ireland, 
and Maine, there is less risk of small seed being injured 
in vigor than in climates too hot and dry for the best 
growth of the potato. The use of the systems of field 
seed selection to find the strain having the greatest 
inherited vigor with seed plots to multiply the selected 
seed produced a stock of which the small culls may be 
saved for use as seed. 

Experiment stations have found conflicting results in 
studying the relative value of eye in different parts of the 
tuber, which need further investigation. The eyes at the 
seed end of the tuber start first to grow and are practically 
the only ones which grow under greening in the sunlight. 
When these seed-end eyes start sprouts, which are broken 
off in handling before the others start the vigor is likely 
to be more equal. Observations indicate that the eyes 
nearest the stem end, particularly with varieties having 
few eyes as the Rural type, are the ones most likely to 
fail to grow and are the ones from which degenerate 
strains originate. Under the present state of knowledge 
of the subject, it is safest for growers to cut seed in such 
ways as to have the seed end eye on as many of the cut 
pieces as possible, and to allow a slightly larger amount 
of flesh to the pieces with stem end eye, to make up for 
their slower starting growth in spring. 

Smaller seed pieces can be used with fertile soil than 



156 The Potato 

with poor soil. The young plant can become established 
and get its nourishment from the soil quicker. 

Whole seed matures the crop a few days earlier, an 
advantage for early high prices, and is less likely to rot 
in cold weather, and to attacks from soil diseases, as in 
Colorado. 

Cutting seed 

Many tools have been invented for cutting seed potatoes, 
but none is able to do as good work as the knife, either 
in the hand or fastened in some way. The Colorado 
cutting rack is a box on legs with slanted or sloping bot- 
tom, having an opening at the side. To the rim of a 
ledge at the front of the operator, a knife is fastened 
with the point vertical. The seed rolls through the ad- 
justable opening at the side to the ledge. The operator 
picks up the seed without motion except that of his hand 
and wrist and cuts the seed by pulling against the knife. 
Some operators prefer to push against the knife, but the 
pulling motion is better because the eyes are then always 
in view, and better judgment can be used in allotting the 
eyes to the different pieces from each potato. The cut 
pieces drop into a crate or sack. Trouble with potato 
diseases of the seed makes it always advisable to have 
some means of disinfecting the cutting knives, even if 
the seed is soaked, as no treatment reaches into the in- 
terior of the tuber. All seed suspected of being danger- 
ously diseased should, of course, be thrown away. A 
dish of formaldehyde solution in which to disinfect the 
knife is advisable. Corrosive sublimate solution is a 
better disinfectant, but is a very dangerous poison to have 
around. 

With the Colorado cutting rack, the operator can do 



Planting 157 

even better work than with the knife held in the hand 
and can cut nearly or twice as fast with less fatigue, due 
to the fact that there is no lost motion in reaching some 
distance for every potato cut. All roll down to within a 
few inches of the hand. The cost is small, being only 
that of a little rough lumber, as the knives can be used 
for other purposes. A knife may be held by fastening to 
a board and potatoes picked from a crate. Any knife 
used in cutting seed should be ground thin and kept 
very sharp. 

Under most conditions a larger yield is secured by 
planting as fast as the seed is cut. The reduction of yield 
of seed allowed to dry may be heavy. Lack of labor in 
planting time often leads farmers to cut seed in periods 
of bad weather and to save the time of cutting later. To 
prevent the loss of seed by heating, it should be kept in 
separated containers, as sacks or crates, with a small 
amount in each in a cool place. 'The moisture on cut sur- 
faces must be dry to prevent heating and rot, but no more 
drying should be allowed. Such carefully dried cut seed 
may do better than freshly cut in cold and wet soil. 
Land plaster (gypsum) may be used to dry cut seed. 
Sulphur has been advocated for disease-prevention, but 
its use does not completely prevent any disease and it 
is very disagreeable to handle. 

The principles of seed cutting are as follows : — 

(1) Seed pieces should be cut blocky in shape to 
make surfaces as small as possible. Blocky pieces feed 
better through machine planters and the smaller exposed 
cut surface reduces loss of moisture and danger of infec- 
tion by rot germ (see Plate VIII). 

(2) The probability in most cases that the seed and 
eyes are more vigorous makes it better to cut each tuber 



158 The Potato 

in such shaped pieces that will give the largest number 
having eyes from the seed end. Seed of size to make two 
pieces should be halved through center of seed end group 
of eyes. Tubers short and round enough to make four 
pieces without their being too long and slender should be 
quartered through the seed end group. Those which 
will make too slender quarters cut in this way should be 
cut once lengthwise and then transversely, making four 
blocky pieces. Many tubers will be the right size and 
weight to furnish three seed pieces. These should be 
cut with one piece taken off the stem end about one-third 
of the length from the stem and the remainder of the 
tuber halved through the seed end group of eyes. This 
gives two out of three pieces with a more vigorous seed 
end eye and the third being cut with a little more flesh 
to make up for the slower start given by its eyes compared 
with those of the seed end. 

Fairly blocky seed large enough for six pieces is cut in a 
similar way, splitting the stem end into two pieces and 
the seed end into four. Seed cutting into more than 
six pieces often has so few eyes, compared with the amount 
of flesh, that it is difficult to cut well, especially towards 
the stem end. The seed end of such large seed should 
usually be cut into four pieces. 

(3) To make sure of one good eye on every seed piece, 
it is well to have two wherever possible. 

(4) The average weight of the seed must be adjusted 
to the needs of the crop for the soil planted. Garden 
soils will need little more than the eye itself to produce 
plants, while soils in very poor condition need large seed 
to furnish nourishment to the young growing plant for 
some time before it can grow roots far enough to support 
itself. The commonest size of seed used runs from one 



Planting 159 

to two ounces. The average amount of seed used to the 
acre in America is estimated at 11 to 12 bushels, the 
range in most cases being from 9 to 16 bushels. Under 
European conditions, growers find it profitable to plant 
larger amounts. In England a long ton, or about 37 
bushels to the acre, is the usual amount and is often 
exceeded. 



CHAPTER VII] 

CARE OF THE GROWING CROP 

l>v Daniel Dean 

The tillage of the potato crop is host considered as a 
connected whole Prom the time of plowing until the last 
cultivation. The results of tillage before planting and 
after, in rendering soil fertility available, in conserving 
moisture and in killing weeds are the same. There is no 
danger of injury to the growing plant before planting, 
Therefore, as large a part o( the tillage of the potato as 
practicable should be done before planting. It' soil 
moisture has been well conserved, plant-food made avail- 
able and a large part o\' the weeds in the soil killed, the 
amount o( the tillage after planting can he largely reduced. 
The danger o( injury to the plants can thus be largely 
prevented. The cost of tillage with wide tools like the 
harrows is less than that of work between rows. Only 
careful men can he trusted io work tools between rows 
without danger, while much poorer labor ran work in the 
open field. When plowing is delayed until just before 
planting, a dry period following will badly injure the crop. 

Tillage is most profitable when given at one particular 
time. After every rain the soil is at first too wet and still' 
to work without injury. It should bo carefully watched 

until in the driest part of the tield it becomes mellow 
enough to work. At this stage, the soil (.Tumbles easily 

160 



Care of the Growing Crop 1G1 

and has passed the time at which stirring will cause baking. 
Stirring the soil at this time saves the maximum amount 
of moisture for the use of the growing crop. Evaporation 
is so rapid that a few hours' delay results in ;i great loss of 
water. The air is usually cool and the soil stirs easily. 
With fresh horses, a large area can be covered in a few 
hours. Weed seeds which have been sprouted by the re- 
cent rains are stirred about and the weeds killed. Grow- 
ing weeds which have escaped previous cultivation are 
torn out and left on top of the soil to be dried and killed 
by the heat of the sun. The potato plants have just 
received the stimulation of needed rain and the dissolved 
plant-food which has been forming in the soil during dry 
weather but not available on account of lack of moisture. 
Under these conditions, the potatoes can stand root 
injury which would be more dangerous at drier times. 

Wide tools can be used in tillage nearly up to the time 
the sprouts break through the surface of the soil. The 
common practice in the principal potato-growing states, 
outside of Maine, of harrowing down the ridges, left by 
the planter or by ridging tools after planting, is very 
beneficial. Plank-floats or clod-crushers are often used, 
but they are dangerous to the growing sprouts. The 
ideal tool for this purpose would be a level which would 
smooth down the ridges without crushing the soil around the 
sprouts. A tool made of plank 2 X 10 inch standing on 
edge and long enough to cover two rows, has been found 
very useful. The driver stands on a horizontal plank 
fastened to the rear of the plank which does the work. 
According to the hardness of the soil, the vertical plank 
is slanted slightly or dropped below the level of the hori- 
zontal plank. Frequent adjustment is needed as the soil 
changes texture rapidly after rains. The horse should be 



162 The Potato 

hitched close to the level to keep it from digging into the 
soil. On any but perfectly level fields, the use of level or 
harrow on more than two rows at a time is likely to result 
either in injury from working one row too deeply or in 
poor work from going too shallow on one and hurting the 
others. Leveling the rows can be delayed longer when the 
seed is covered deeply. Many stones in the soil make it 
advisable to level earlier if it can be done at all on account 
of stones moving the seed. 

A practice used much in Maine and suited to wet and 
cold climates is to ridge the potato rows just after the 
plants come up. If frost follows, the plants are safe from 
it for several days longer than if left uncovered. Such 
ridging kills many weeds, but is suited only to sections in 
which the soil is sure not to bake over the little plants, and 
to conditions of damp soil which make ridging the best 
practice. 

Without heavy ridging late in the season, the weeds 
hardest to control are those closest to the potato plants. 
Thorough stirring before the plants come up and a fre- 
quent use of the weeder afterwards enables one to control 
the weeds near the plants as easily as those between the 
rows. 

Many forms of cultivators are made for tilling the soil 
between the rows of potatoes. Very heavy soils, such as 
those of the Greeley region of Colorado, need four-horse 
cultivators which use two teeth four inches wide and four- 
teen inches long on each side of the row and stir the heavy 
clay to the depth of eight or ten inches. Other cultivators 
for light sandy soils may merely stir the surface with twelve 
or fourteen peg teeth. Between these types, every grada- 
tion of size and number of teeth may be found according to 
the soil conditions. 



Care of the Growing Crop 163 

As a general rule the first cultivation after planting is 
made as deep and as close to the seed as possible, because 
the potato roots have not started far yet and are safe from 
injury. The soil settles together so quickly that it should 
be kept mellow in this way as long as possible. Sometimes 
a second deep cultivation may be given. Later cultiva- 
tions after the roots start are made with the teeth working as 
shallow as they can be made to work, so as to form a mellow 
soil mulch. This depth will vary in different soils from one 
to three inches. Measurement will show that cultivator 
teeth often work much deeper than the grower is aware. 
As the tops begin to grow and form a mass, the cultivator 
teeth can be narrowed. Weeds start less in the shade of 
the tops and evaporation becomes less, partly on account 
of the shade and partly because surface roots form to use 
the moisture. Wide, deep teeth are manufactured to 
cut the roots of perennial weeds like the Canada thistle. 
Such teeth may often be substituted in part for the com- 
mon teeth. Cultivators are made for one, two, three or 
four horses, with wheels and without, and for the driver 
to walk or ride. One-horse walking cultivators, common 
in the East and South, have great disadvantages. Even 
when fitted with wheels in front to regulate the depth, the 
teeth cut much deeper in some soils than in others. The 
machine is too light to hold in the soil in stony ground. 
Masses of weed roots, like those of quack- or witch-grass, 
clog the teeth and cause the teeth to rise out of the soil at 
the very places where the best work is needed. Wheel 
cultivators enable one to regulate the depth of working to 
better advantage. The weight of the wheel cultivators, 
with that of the driver, holds the teeth into the ground 
among stones and weeds. The wheels prevent the teeth 
from cutting too deeply in mellow places free from weeds. 



164 The Potato 

Deep cultivation is most dangerous in dry times. The 
gain from weed killing may be offset by the loss of the 
potato roots. 

A tool which is used less than it should be is the weeder. 
Weeds like ragweed, foxtail or barn grass, pigweed and 
the whole class which grow from small seeds in the potato 
field are very easily killed by the frequent use of the weeder 
until the potatoes are nearly a foot high. Weeders are 
made with either two or three rows of teeth, with wheels 
and without and with different styles of teeth. The prin- 
ciple is the same in all, that the light and somewhat flexible 
teeth tear out and destroy the tiny weeds starting in the 
surface soil with little or no injury to the larger sized potato 
vines. The weeder is a tool which demands certain soil 
conditions to be effective. It will not work at all on hard 
soil. Many growers have discarded weeders after trying 
them where the soil was not suited to their use. Most 
soils have a short period after every rain when the flexible 
weeder teeth are able to penetrate and stir the soil. If 
that time is taken for their use, many sprouting weeds 
can be killed in a very short time and the surface mulch 
established close to the potato plant. The weight of the 
weeder selected and the stiffness of the teeth should be 
carefully chosen according to the character of the soil. If 
necessary, weight can be added. A needed precaution in 
the use of the weeder is to keep the teeth free from trash. 
Weeders are often used to follow a cultivator with large 
teeth to better level the soil between the rows. Weeders 
and leveling tools, like the harrow, are sometimes driven 
crossways of the potato row. It may be possible to do 
the work a little better in this way, but the danger of injury 
to the growing sprouts and roots of the potatoes from 
crushing under the feet of the horses is so great that it is a 



Care of the Groiving Crop 165 

practice of doubtful advantage. In most cases, practically 
all of the weeds can be killed by driving along the row. 
The weeder is a tool for prevention of weeds rather than 
their cure. It will not kill those which have got much of a 
start above the soil or those with underground rootstocks 
like quack-grass. 

A comparison of potato-growing of 1916 with that of 50 to 
75 years ago shows how great has been the substitution of 
tools operated by the power of animals for those worked by 
man. Where formerly the plow and harrow were nearly 
the only tools not worked by hand labor, the farmer may 
now use the horse-drawn planter, fertilizer-sower, manure- 
spreader, numerous types of cultivators, weeders, ridgers 
and other tillage tools, the sprayer and the different types 
of diggers. 

Within the last twenty years the gasoline engine has 
been developed to a wonderful degree. Millions have been 
built for automobiles and probably millions more have 
been sold for farm use, for threshing, feed grinding, pump- 
ing water and other uses. Gasoline tractors are being 
rapidly developed to draw farm tools in the field. As yet 
they have been little used in potato-growing except for 
plowing and harrowing. A great obstacle to the use of 
present tractors between potato rows is the width of a track, 
usually four or five feet. Potato rows are usually about 
three feet apart and tools for work between the rows must 
have a tread of about three feet, or else have a six-foot 
tread, like most potato sprayers. Four-wheeled tractors 
used to draw tools need two operators, one for the tractor 
and another to handle the tools. On any but perfectly 
level land the side movements of front or rear wheels in 
skidding quickly injure the potato plant. New types of 
tractors are being developed by which the same two wheels 



166 The Potato 

are used for driving and steering, the tool itself taking the 
place of the other wheels of the tractor. One operator 
handles both engine and tools. Similar small engine- 
propelled tools are being made for garden use. 

Engines are being used on potato sprayers to give better 
results by higher pressures than horses can furnish. The 
elevating and separating machinery of potato diggers is 
sometimes driven by engines, horses being used to draw 
the tool only. 

Harrows or leveling tools are usually used once; occa- 
sionally twice. Weeders may be used up to a dozen times 
in extreme cases and half a dozen pay well. Cultivators 
are used from three to eight times with four or six as 
the most common number. Outside of Maine, the ridging 
tools are used once or twice. Thorough tillage and a good 
condition of the soil before planting necessitate less work 
later. It is a good rule to cultivate after every heavy 
rain, and to cultivate more frequently in hard soils than in 
light. Tillage is less needed in soils which are mellow and 
full of organic matter, because such soils supply plant-food 
and water more readily. 

The danger of the growing tubers protruding out of the 
soil and being sunburned is prevented by ridging lightly 
after the tubers are formed. Ridging earlier does not pre- 
vent sunburn because the depth at which the tubers form is 
controlled by the depth of planting. Very shallow plant- 
ing results in the tubers forming below the seed and very 
deep planting in forming at a depth where little sunburn- 
ing results. Usual depths of planting are not deep enough 
to entirely prevent sunburn. While late ridging is some- 
what feasible, the difficulty is that any injury to the roots 
of the growing potato plant at that stage is dangerous. 

Tillage is so necessary in potato-growing for the libera- 



Care of the Growing Crop 167 

tion of plant-food, maintenance of healthful soil conditions, 
saving moisture and weed killing that it must be practiced 
after planting the potato crop. As the potato plants are 
more tender than most weeds, great injury may result from 
careless tillage. The tender white sprouts starting from 
the seed tubers are usually injured by a touch. The soil 
about the seed may be thoroughly stirred with a harrow 
and level during the first few days after planting without, 
danger. The weeder can be used with good results in 
killing weeds and keeping a soil mulch above the plants 
if great care is used to prevent the teeth from injuring the 
sprouts. If the number of injured sprouts is small, the gain 
from the tillage may outweigh the setback which the in- 
jured plants receive. 

The next period, from the time the plants form green 
leaves above the ground till the tops are eight to twelve 
inches high, is one when the benefits of tillage are usually 
greater than possible injury. During a large part of the 
time the plant-food in the seed tubers is still available, and 
the leaf surface is not yet large enough to transpire enough 
water to seriously injure the plant. Sun-scald and tip- 
burn are not common until the plants are larger. Roots 
are being developed close around the seed and stalks. 
Until the roots are numerous enough for tillage to destroy 
more than a small proportion of the whole root system, 
tillage is beneficial. Later the horizontal roots extend 
until they cross between the rows. These roots are now of 
the size to make their injury a serious matter to the grow- 
ing plant. The greatest development of the roots is in 
the plowed area, or five to ten inches below the surface. 
Many roots also extend down to the depth of three to four 
feet. A large part of these vertical roots drop downward 
from the large horizontal roots close to the surface. It is 



Las Potato 

vei j : i ■ ■ s ■ ' \ i ! late in 

the season without cutting these lateral foots, The loss 
of FOOl ' - ' • further iuereased by the loss ^{ (ho \v 

roots attached to these lateral ones 

The of the value of those roots to the yield of 

the crop - ■ * ital One function o! the roots of the growing 

i is to take iu water containing plant-food in solution. 

■ is transpired from the leaves and the plant 

food transformed into material for further growth of the 
plant. Transpiration from the te i\ es of the potato is loss 
easily checked in periods of drought than with many othei 

potato lias loss ability to regul WSC of 

w i te b$ the supply available, Removing part of the 
leaves by pruning or b) vs of disease reduces the yield 

;-n dking away from the plant the factory in which the 
material for the tubers is elaborated, As the supply of 
ood remains the same, svieh pruning may 
even be of benefit m the eases where tl te aormal food 
supply • The removal of part of the roots not 

only removes a fraction of the supply ^( watei tnd food, 

but, from the nature of the plant, throws it out of balance, 

The leaves continue to transpire water, and in the lack of 

full supply from the root, use up part of the water iu the 
plant itself. The whole plant sutlers, the greatest injury 

showing at the - ■ • the leaves The ends of' the leaves 
dry up ami die, a trouble commonly called "up-bum." 

The strain upon the potato from exhausting etleets of 
blossoming ami forming tubers at nearly the sante time is 

w\ 'v.:\\ i"v heat and drought which often occur at 
this time the troubles of the plants. Any damage 

to the plant is now more dangerous than before. At this 
time, tillage may be beneficial or may be very injurious. 
If the weather is eool ami the soil water ample, tillage may 



Care of the Growing Crop 169 

greatly increase the crop. Hot and dry weather, at or 
following the time of tillage, may nearly ruin the crop, 
weakened by root injury. 

Tillage so loosens the upper inches of the soil that the 
roots cannot develop there until after tillage stops. The 
plant-food contained therein may be of great value to the 
growing crop. Exhaustive experiments show that with 
corn practically the same amount of water is found in the 
soil late in the season whether tilled or not. The plant 
roots are able to use the water before it can escape from the 
surface. 1 If weeds have been killed, there is little need of 
stirring the soil late in the season. The frequent grinding 
of the upper soil layer by early tillage has changed much 
of its contained plant-food into a condition in which it is 
available to the plants. If the previous care has been such 
that the crop has passed the critical period in good condi- 
tion, the roots soon fill the surface soil and use the plant- 
food supply for the production of tubers. A few weeds 
which may have escaped the tillage tools should be pulled 
by hand in July and August before they go to seed. 

Spraying is commonly thought of only in its relation to 
insects and diseases. Thorough spraying with bordeaux 
has been found to give an increase in yield in the absence 
of disease and insects. This action is noted most in hot 
and dry seasons. It should always be considered among 
the methods to insure good yields in sections where heat 
and drought are likely to limit the yield. 

1 111. Bui. 181. Bui. 257, Bur. PI. Ind., U. S. Dept. Agr. 



CHAPTER IX 

POTATO INSECTS AND THEIR CONTROL 

The amount of damage to the potato crop by insects 
is very large, much larger than is ordinarily supposed. 
Spraying with poisonous substances has to be resorted to 
in order to obtain a crop which has been uninjured by 
insects. They do four kinds of damage and may be clas- 
sified in this manner : (1) insects chewing the leaves ; 
(2) insects sucking the leaves and tips ; (3) stalk borers ; 
and (4) insects affecting the tubers. Most of the damage 
is done by the Colorado potato-beetle and the flea-beetle. 

The Colorado potato-beetle (Leptinotarsa decemlineata) 
(Fig. 10). 

This is a leaf-eating insect, and its ravages are very 
general. It seems to be always present where potatoes 
are grown, and the damage it causes is very great. Indeed, 
in most sections, it is impossible to obtain a crop at all 
unless its ravages are held in check by the application of 
some poisonous substance to the leaves. 

This insect is a native of a strip of country which lies 
just east of the Rocky Mountain range and includes eastern 
Colorado. In its native state the beetle lives upon the 
wild weeds of the potato family, the chief of which is the 
sandbur (S. rostratum). It is a general feeder, living on 

170 



Potato Insects and their Control 17 1 

not only potatoes, but tomatoes, eggplants, tobacco and 
peppers. 

"It was first brought to notice," says Geo. C. Butz, 
"about the year 1856. In 1861 it was found in the potato 
fields of the settlers of Kansas. In 1862 it was in Iowa, and 
in 1862 it appeared in southwestern Wisconsin. It crossed 
the Mississippi River into Illinois in 1864. It was in 
Michigan and Indiana in 1867, Ohio in 1868 and Pennsyl- 
vania in 1870. It moved eastward at the rate of about fifty 
miles a year for a number of years, but later it traveled 
more rapidly. It is reported to have reached the Atlantic 
Coast about 1874, and Nova Scotia about 1882. When it 
reached the Atlantic Coast, it had traveled 1500 miles in 
sixteen years, and nearly 1000 miles more the next eight 
years in its march to Nova Scotia." 

The mature beetle hibernates in winter in the ground 
usually at a depth of eight to ten inches and begins to fly 
early in the spring. As soon as the first leaves of the po- 
tato appear above the ground, the beetles fly to them and 
soon lay their reddish yellow or orange-colored eggs in 
clusters on the under side of the leaves. In about a 
week the young beetles or larvae appear and begin to 
devour the foliage with great rapidity. The larvae 
pass through four stages or instars and are mature in 
sixteen to twenty-one days, according to the weather. 
Then they go into the ground and transform into the pupa 
or resting stage, in which they remain at least a week — 
usually longer — before coming out as the adult beetles. 
The egg-laying period lasts about thirty-five or forty days. 
The minimum time for the life cycle is about four weeks. 
The last brood of larvae which disappear into the soil 
before severe frost pupate there, remaining in the ground 
in the form of perfect insects until the following spring. 



172 



The Potato 



The adult beetle is oval in shape, about three-eighths of 
an inch in length and a trifle narrower than long. The 
ground is yellow and the wings are marked by ten black 
lines running lengthwise. There are also black markings 
on the thorax (see Fig. 10). These insects have great 
power of endurance. They will walk for great distances in 
search of food, and it is said by direct experiment they are 
known to have lived thirty days without food. Their 
eggs are a bright yellow when fresh and the young are 
dark red or brown grubs with black heads and markings 

of black spots in double rows 
on each side. The color be- 
comes lighter as the grubs 
mature. 

Control. — The Colorado 
potato-beetle is controlled by 
the use of poisonous sub- 
stances which either in solu- 
tion or suspension are sprayed 
upon the vines. The most 
common of these arsenical poisons are paris green, arsenate 
of lead or arsenate of soda. Any one of them may be 
sprayed upon the vines alone or mixed with bordeaux mix- 
ture and applied. Poison is usually necessary only for the 
first two regular sprayings, but should be added at any time 
the larvse become numerous. The eggs should be watched 
carefully, and after they are well hatched and the young 
have begun to feed, the first application of the poison 
should be made. A second spraying will doubtless be 
necessary in ten days to two weeks. The necessity for 
subsequent applications of poison will be determined by 
any later appearance of the pests. The first sprayings 
should not be delayed too long, as the larvse develop very 




Fig. 10. Potato bug, larva and 
mature beetle enlarged. 



Potato Insects and their Control 173 

rapidly after hatching and much harm is often done before 
one is aware of it. With fifty gallons of water, if the poison 
is to be used alone, or of bordeaux mixture, use three to 
five pounds of arsenate of lead or one pound of paris green, 
and add two pounds of quicklime to prevent burning. 
One pound of paris green to the acre in either water or 
bordeaux mixture is ordinarily recommended. Growers 
should be warned against the use of excessive quantities of 
paris green because it burns and injures the vines if put on 
too strong. Arsenate of lead has the advantage of adher- 
ing to the vines and is only slightly washed off by rains. 
After long-continued rains, the vines may often be seen 
to be grayish in color because of the arsenate still clinging 
to them. When these poisons are applied with water, 
whether with or without bordeaux mixture, some provision 
must be made to keep them constantly agitated so that 
they will not settle to the bottom of the spray tank. 

Flea-beetle (Epitrix cucumeris) (Fig. 11) 

This is a leaf-eating insect. There are several kinds of 
flea-beetles which are troublesome to potatoes, the one 
named above being the most common. In the South the 
tobacco flea-beetle {Epitrix parvula) and the eggplant 
flea-beetle (Epitrix fusculd) do considerable damage. 
Another larger, more elongated form, known as Systena 
hudsonias, has been found to cause considerable damage 
in the North. 

These flea-beetles all belong to the leaf-chewing class. 
The adult beetles frequently do much damage to the 
potato crop, but being so small, less than one-twentieth 
of an inch, they are often not seen. They are black and 
jump when alarmed, which also makes it difficult to see 




174 The Potato 

them. The result of their depredations will be found in 
the many small holes which may be noticed in the leaves 
of the young potato plants, and in the lessening of the 
crop on this account. These many small holes make 
excellent starting places. for many diseases to get a foot- 
hold to injure the plant. The beetles stay mostly on the 
under side of the leaves and are not seen, their presence 
being detected only by their work. The larva? occasion- 
ally do injury by mining into the 
tubers and cause pimply potatoes. 
During the hot, dry summers, 
especially, they often become the 
worst enemies of the potato. The 
insects very often congregate in 
such numbers that the leaves of the 
Fig. 11. Flea-beetle, plants appear almost black with 
them. Young potatoes and newly 
set tomato plants frequently have their leaves so badly 
eaten that they shrivel, and the tomatoes may die. 

The life histories of the different flea-beetles are prac- 
tically the same. The adult insects live over winter under 
leaves and rubbish and appear during the latter part of 
May and first of June. As soon as they come out, they 
lay eggs near the roots of the potatoes or of weeds related 
to them. The larvae mine into the roots; and when full 
grown, they pupate and later emerge as adult flea-beetles. 
In some sections, particularly in Colorado, the greatest 
damage is done by the larva?, which are tiny white grubs 
about a quarter of an inch in length. They frequently cut 
into and destroy the young tuber stems of the potato and 
prevent a regular setting of the crop. 

One brood of potato flea-beetle appears yearly in the 
North and two broods in the South, the second ordinarily 



Potato Insects and their Control 175 

appearing in August and September. This brood, coming 
at a time when the tubers are partially or wholly grown, 
bores into the flesh and underneath the skin of the potato, 
causing a pimply or scabby appearance which detracts 
from their market value. 

Control. — Flea-beetles are very largely controlled by 
bordeaux mixture, which acts as an effective repellant. 
They ordinarily feed, however, on the under side of the 
leaves, and thorough spraying both on the upper and lower 
sides of the leaf is necessary to be satisfactorily effective. 
Spraying may have to be begun somewhat earlier for the 
flea-beetle than for other insects or diseases. The insects 
are so small and their damage begins on the under side of the 
leaves, so that often a great amount of damage may have 
been done before it is detected. It is a good practice to 
eliminate from the farm such plants of the solanacese fam- 
ily as nightshade, bitter-sweet, horse-nettles, ground cherry 
and jimson weed. The flea-beetles breed on these as well 
as the potato itself. 

Blister-beetle (Epicauta and Macrobasis) 

These are leaf-eating insects. The so-called "blister- 
beetle" or "old-fashioned potato-bug" consists of four or 
five species of insects which do a tremendous amount of 
damage to the potato in some years. They sometimes 
appear in great numbers and are not easily vanquished. 
They are all medium-sized elongated beetles of different 
colors : spotted, striped, black, light or dark gray. The 
adults damage the potato plant, but the larva? are especially 
beneficial in destroying the egg masses of the grasshoppers. 

A large number of eggs are deposited by the female in a 
small cavity in the ground. The larvae are provided with 



176 The Potato 

legs by which they crawl about until they find a grass- 
hopper's egg mass, upon which they feed. They then molt, 
their legs becoming rudimentary. As helpless grubs they 
complete the remainder of their larval stage surrounded 
by an abundance of food. There is one brood a year. 

Control. — If potatoes are carefully sprayed for the 
Colorado potato-beetle and flea-beetle, there will be little 
danger from the attack of these insects. Sometimes, 
however, they appear in large numbers and should be im- 
mediately killed by additional applications of arsenical 
poisons. 

The three-lined leaf-beetle {Lema trilineata) 

These leaf-beetles are leaf-eating insects. Both the 
adults and larvae of this insect feed on potato leaves. This 
beetle is smaller and more elongated than the Colorado 
potato beetle and has only three black lines on a yellow 
ground color. The larvae are distinguished by having their 
backs covered with their own excrement. 

The adults hibernate over winter and come out in the 
spring, laying their eggs on the underside of the potato 
leaves along the veins. There are two broods a year ; the 
larvse of the first brood appear in June and those of the 
second brood in August. The adults of the second brood 
go into the ground to hibernate over winter. 

Control. — This insect is controlled in exactly the same 
way as the blister beetles. 

Tortoise-beetles {Cassida and Coptoeycla) 

Tortoise-beetles are leaf-eating insects. The insects 
of these genera are of minor importance, but may do some 
damage in unsprayed fields. Their oval shape and flaring 



Potato Insects and their Control 177 

edge of the thorax give them some resemblance to a 
tortoise shell. They are of small size and green, gold or 
black in color. 

The adults make their appearance in May, having lived 
through the winter in crevices under bark and in similar 
dry places wherever shelter could be found. The female 
begins to lay eggs soon after her appearance. The eggs 
are laid singly on the leaf-stems or on the under side along 
the larger veins, and each is covered with a little daub of 
black excrement, so that all that is visible to the eye is a 
little mass of black, pasty material that soon hardens. 
This mass incloses the whitish oval egg and protects it. 
During the first part of June, many of the eggs have 
hatched and larvae, eggs and adults may be found on the 
plants all at once. "The larvae are decidedly flattened, 
more or less oval, with lateral spines or processes from the 
margins, and at the end of the body is a fork which, in 
some species, holds all the excrement voided during life 
and sometimes the cast skins as well, often making a mass 
nearly as large as the larvae itself." These feed, pref- 
erably, on the under surface of the leaves and do much 
damage. The larva pupates about the middle of July. 
The beetles appear during early August and feed very little, 
all trace being gone before the beginning of September. 
There is one brood a year. 

The potato plant-louse (Macrosiphum solanifolii) 

This plant-louse is relatively large in size, and either pink 
or green in color. Its mouth-parts, like those of all plant- 
lice, are adapted for sucking the juices from the tender, 
growing tips of the vines. The infested vines grow brown 
at the ends and often die back for four or five inches. In 



178 The Potato 

certain seasons, these insects become very numerous and 
their depredations check the growth of the vines con- 
siderably. The wounds made by the beaks of the aphids 
often admit fungi and indirectly result in greater injury 
than the work of the insect alone. 

The potato aphid passes the winter in the egg stage, 
the eggs being attached to weeds. In the early spring, the 
adult insects are to be found feeding on the succulent tips 
of rose bushes. In July, the aphids migrate to potato 
fields and start feeding there. The potato seems to be an 
ideal food for this insect, for it increases in numbers very 
rapidly, a single female often producing over fifty young 
in two weeks. Late in August or early in September, 
the lice leave the potato vines and go to rose bushes or 
other food plants. Here they produce several more 
generations of young. The last generation of the year 
consists of wingless females and winged males. The 
females lay the over-wintering eggs on the shepherd's 
purse, potato, and other food plants. 

Control. — There are certain natural agencies of control 
over these insects which frequently make them of little 
consequence. Among these are cold weather, frequent 
rains, parasitic fungi and insects, and various predacious 
insects. These factors cannot be relied upon, however, 
to keep the pest in check every year. Fall plowing will 
turn under many weeds and old leaves on which the eggs 
have been laid. It has also been suggested that the 
farmer burn the dead vines in the fall in order to destroy 
the eggs. The adult insects can be killed by using any 
good contact insecticide like one of the tobacco extracts, 
kerosene emulsion and the like. Spraying is usually only 
resorted to when the insects become very troublesome. 



Potato Insects and their Control 179 

Leaf-hoppers (Empoasca mail) 

These leaf-sucking insects do some damage to potato 
tops by sucking the juices and making holes in the leaves. 
The most common of the leaf-hoppers is Empoasca mali, 
which is a small, elongated, pale-green insect, very active, 
jumping and flying readily. 

This insect spends the winter either in the adult or in 
the egg stage. It appears in the spring and starts to feed 
upon the apple or other food plants, and soon lays its eggs. 
The nymphs from the over-wintering eggs are found about 
the middle of May. Usually about four broods develop 
during the season. The leaf-hoppers are generally all gone 
by the first of October. 

Control. — They do not require special treatment, never 
appearing in sufficient numbers to do any great damage. 
Treatment for other insects readily keeps them in check. 

The potato-stalk weevil ( Trichobaris trinotata) 

This is a stalk-boring insect which does considerable 
damage in the south central states. The adults are small 
ash-gray beetles with a long snout, and the larvae are small 
white grubs. 

The adults appear in the spring after hibernation and 
eat holes in the base of the stalk with their long snouts and 
deposit an egg in each hole. These soon hatch, and the 
larvse make their way into the main stalk and branches. 
These grubs become full grown near the middle of August, 
and then they pupate in cocoons which they have spun 
near the base of the stalks. Adults appear a week later 
and remain in the stalks until the following year. 

Control. — Since the adults hibernate in the old stalks, 



180 The Potato 

the best method to keep them in check is to rake the fields 
over after digging the potatoes and burn all the refuse. 
Destroy also all other solanaceous plants which may be 
growing in the neighborhood. 



The stalk-borer (Papaipema nitella) 

The potato is probably not the normal food plant of this 
insect, but when other food material, such as certain weeds, 
tomatoes, corn, cotton and some grasses, are lacking, the 
potato is sometimes infested. The adult is a gray moth, 
and the larvse do damage by boring into the stems of the 
plants on which they feed. 

The insect lives over winter by means of eggs which are 
laid in the fall in masses of fifty or sixty on grasses and 
weeds. The eggs hatch in the spring, and the larvse 
puncture the leaves and then work down into the stalk. 
Frequently they travel from one plant to another. The 
larvse, when mature, eat holes in the sides of the stalks and 
pupate. Late in August, the adults emerge and lay eggs 
for next year's flock. There is one generation in a year. 

Control. — The stalk-borer should have the same treat- 
ment as the stalk-weevil. 



White grubs (Lachnosterna species) (Fig. 12) 

These are the larva? of the May-beetles or June-bugs. 
They are large, white, soft-bodied grubs which are com- 
monly found in sod ground. They feed on the roots of 
many plants and sometimes eat into the tubers of pota- 
toes, especially those planted on new ground. 

This insect lives in the ground over winter either as an 



Potato Insects and their Control 



181 




adult beetle or as white grubs. It takes two or three 
years to complete its life cycle. The adults lay eggs in 
sod ground in June which hatch in about two weeks. The 
larvse or grubs feed on roots and require one or two sum- 
mers to become fully grown. 
They pass the first winter as 
grubs living deep down in the 
ground and the second summer 
are much larger and more 
destructive than the first, so 
that those fields left in sod one 
year are likely to be badly in- 
fested the next year. The 
larva, ordinarily, pupates in 
June or July of its second year 
and after remaining a pupa for about three weeks, changes 
into an adult beetle and remains in the ground until the 
next spring. 

Control. — If the ground is badly infested with white 
grubs or wire-worms, it should be given a thorough fall 
plowing and either plowed again or thoroughly harrowed 
in the spring. Land which has been in sod for many years 
would ordinarily need this treatment. Potatoes should 
not be planted immediately upon such ground, but it 
should be planted for a year or two to such crops as buck- 
wheat or some of the other small grains which are damaged 
but little by white grubs or wire-worms. 



Fig. 12. White grub and 
May-beetle. 



Wire-worms {several species) (Fig. 13) 

These insects do much damage to the roots of many crops, 
including the potato. Like the white grubs, they normally 
live in sod ground and feed on roots, and are not usually 



182 



The Potato 



injurious to potatoes unless the ground has been in sod a 
year or two. Wire-worms are the 
long, hard, cylindrical larva? of the 
click beetles. They include several 
species. 

Like the June-bugs, the eggs are 
laid on sod ground and the larvse 
require from three to five years to 
mature. They transform to adults 
under ground in midsummer, but 
usually remain in the soil until the 
following spring. 
Control. — See methods of control of white grubs. 




Fig. 13. Wire-worm 
and the beetle. 



CHAPTER X 

DISEASES OF THE POTATO 

Br M. F. Barrus 

When healthy potatoes are planted in a warm, moist soil, 
vigorous sprouts will grow up from the tubers. These 
develop into vines with green expanded leaves. On 
underground stems there will be formed young tubers 
which enlarge greatly in the latter period of the growth 
of the plant. When the healthy tuber is planted, the 
food stored within is used for the production of tissue 
for roots, stems and leaves. As soon as the leaves have 
expanded they perform the important task of making 
food during daylight from the carbon dioxide of the air 
and from water and soil solutions absorbed by the roots. 
This food is used for the maintenance and further growth 
of the plants, and whatever is made in excess of this is 
stored in the tuber largely in the form of starch. After 
the vines have obtained their greatest growth, the leaves 
make a large excess of food above that needed for main- 
tenance, and consequently the storage of food in the tuber 
takes place rapidly. It is plainly to be seen, therefore, 
that in order to have a large amount of food stored in 
the tubers, that is, to have a large yield, it is necessary 
first to have a good growth of vines and to have them 
remain healthy until the tubers become of maximum size. 
A destruction of the leaves by any means reduces the 
yield of tubers. 

183 



184 The Potato 

When the leaves of the plant become crinkled and 
curled, mottled, rolled, spotted, blighted or dead at the 
edge, when the vines show a yellowing and wilting, or 
become stunted, or the stem shows discolorations on the 
outside or within, or when the tubers have rough scabs 
or pustules or show rotted areas, or the tissue within is 
streaked with brown or is decayed, we say the plant is 
diseased. Any one of these appearances, called symp- 
toms, may indicate the presence of disease, and its appear- 
ance means that the plant is unable to produce its maxi- 
mum yield. It is to the interest of the farmer to know 
what these diseases are and especially to know how to 
prevent them. 

A plant, like a person, may be small and also be healthy. 
Poor soil often produces small plants, and late planted 
tubers may produce vines which may be killed by frost 
before they have attained their maximum growth. Such 
small plants are not diseased. Other things being equal, 
however, small vines will not produce as large yields as 
large vines. But plants may be small because they are 
affected by some disease, so that it is often difficult to 
tell whether small plants growing in a field are affected 
by disease or are small for other reasons. Some plants 
grow "all to vines," that is, the vines continue to grow 
vigorously all the season and by so doing use up a large 
amount of the food made by the leaves so that there is 
but little left for storage in the tubers. Such plants 
usually have small or unmarketable tubers. This condi- 
tion may be brought about by too much shade or by a soil 
too rich in nitrogen. On the other hand, such a condition 
may be the result of a disease known, for the want of a 
better name, as "large vines and many small tubers." 

A disease of a plant is an abnormal condition which 



Diseases of the Potato 



185 



prevents it from completely carrying on its life processes 
and producing its fruit naturally. There are many 
agencies capable of bringing about disease of the potato, 
some of which are not well understood at present. Disease 
may be brought about by conditions of soil and climate 
unfavorable to the 
plant, by physiologi- 
cal disturbances within 
the plant, the direct 
cause of which is not 
clear, and by the 
attacks of parasitic or- 
ganisms. Troubles re- 
sulting from the first- 
named condition may 
sometimes be reme- 
died by selecting vari- 
eties or types of plants 
better adapted to the 
climate in which they 
grow, or by adopting 
a system of culture that will overcome or obviate the 
unfavorable condition. The second group of troubles 
are often heritable, and the only means of avoiding them 
are through the elimination of tubers from affected 
vines for planting purposes. The third type of disease, 
and often the most destructive, is caused by parasitic 
organisms and may be communicated to healthy plants 
by the transfer of the parasite or some special portion of 
its body adapted for the purpose. 

For convenience in discussing them, we may classify 
parasites of the potato into plant and insect parasites. 
The plant parasites include fungi, bacteria and slime- 




Fig. 14. Section through a part of a dis- 
eased potato leaf, showing the spore stalks, 
with spores attached, extending down 
through the breathing pores of the leaf. 



LS6 The Potato 

molds. A fungus is itself a plant, but without loaves or 
green color. It is not able to prepare its own food as 
higher plants do, but must live upon the product of other 
plants. Many fungi and bacteria and most slime-molds 
are saprophytes, that is, they obtain food from the prod- 
ucts o( plants or animals that are dead. Others are 
parasites — obtaining their (ood from the products of 
living plants by attacking the living tissues, injuring or 
killing them and thus causing a diseased condition in the 
plant or the death of the entire plant. 

A fungus differs from a higher plant in that it does not 
have roots, stems or leaves in the sense in which we 
generally regard these organs, but in its vegetative stage 

it consists of tiny thread- 
like tubes or strands 
known collectively as 
mycelia. The mycelium 
penetrates the food ma- 
terial and obtains its nu- 
trition from it. After a. 
period of growth the 
mycelium produces its 
fruiting body which va- 

CAfter as. Dept. A g ro ries greatly in size, shape 

Fig. 15. Below from right to left and condition in the dif- 

are shown four stages in the formation ,. , ,. • mi j> •■ 

of swam, spores. The way in which f erent fun S L l ho frUlt " 

the swarm spores germinate is shown ino- body bears the re- 
above, i ,•' i j- i 

productive bodies known 

as spores (Fig. L5), of which enormous numbers are 
usually produced. These are disseminated by water, air 
or animals, depending on the kind o\' fungus producing 
them. When spores of parasitic fungi fall upon their 
host plant, that is, the plant from which they are able 




Diseases of the Potato IS7 

to extract, their food, they will germinate under favorable 
conditions of temperature and moisture, [ndeed most. 
spores will germinate under favorable conditions without. 
the presence of the host plant. These conditions vary 
with different fungi, but, in general, a fairly warm, moist 
condition is favorable for the germi- -^ 

nation of most spores. The sprout, - u' Y A\ \j, jj ^ 
or germ-tube (Fig. !(>">, produced by rt r ^ w 1iCT*lfr|Pif 
tlie germinating spore enters the tis- n • ' | 

Sue of the host directly through the ' 

wall which it is able to dissolve, . Vu> - "'' i*"!^" 

' in,": swarm spore, show- 
through WOUllds or through the ing germ-tube entering 

breathing pores. The root-hairs of 

higher plants have very tender walls, and these may serve 

as a point of infection by parasitic fungi of the soil. After 

a fungus gains entrance to a plant, it lives upon the cell 

products and usually brings about the death and discol- 
oration of the tissue's at the point, so that the infested 
area, may be seen as a spot, rot, blight or canker. The 
fungus, sooner or later, puts forth fruiting bodies on the 

OUtside of its host, and on these bodies the spores arc 

borne. 

Bacteria, are plants of a lower order than fungi, many 
kinds consisting of but a single minute cell. In the 
presence of oxygen, water, food and suitable temperature 
they reproduce very rapidly. They do not produce 
spores like fungi, and are unable to penetrate unaided 
the outer tissues of plants, but may cuter (he plant 
through insect and other wounds or through Other open- 
ings. Thus, parasitic bacteria may be carried from plant. 

to plant by insects and be introduced into their tissues 
during dry weather when fungi would be unable to do 
so. Bacteria also live entirely within the host plant and 



188 



The Potato 



do not produce fruiting bodies on the exterior, though 
the living bacteria may ooze out with the sap through 
wounds or breathing pores. 

Most slime-molds are entirely saprophytic, though a 
few attack living plants. The one producing powdery 
scab is the only example of a slime-mold disease of the 
potato. The slime-mold differs from a fungus or a bac- 
terium in that it consists of a naked mass of protoplasm, 
often of many cells, in its vegetative stage. The spores 
of the one producing powdery scab germinate as a tiny 
mass of naked protoplasm which gains entrance to its 
host through the lenticles or breathing pores on the tuber. 
It passes from cell to cell within its host, infesting the 
contents and itself greatly increasing in mass. Finally, 
its body is transformed into spores which become exposed 
with the rupture of the skin above them. 



CLASSIFICATION OF CAUSES OF DISEASE 

According to their causes, we may classify the diseases 
of potatoes as follows : 

Fungous — Early blight, late blight, and rot, 
Fusarium dry rot, Fusarium 
wilt, Verticillium wilt, rhi- 
zoctoniose, wart, and silver 
scurf. 

Bacterial — Common scab, black leg, soft 
rots, bacterial wilt, streak. 

Slime-mold — Powdery scab. 
Non- f Curly dwarf, leaf-roll, mosaic, spindling sprout, 
parasitic j net necrosis, tip-burn, arsenical injury. 



Parasitic 



Diseases of the Potato 189 

Early blight (Plate X) 

Early blight, caused by the fungus Alternaria solani, 
appears as angular, dark brown dead spots on the leaves, 
which may become so numerous as to kill the entire leaf. 
The spots are marked with concentric rings of elevation, 
giving the dead area a target-board appearance. The 
vines usually do not become affected until after blossom- 
ing has occurred, but may then become so severe as to 
cause the vines to die. The spots often occur around a 
flea-beetle puncture or other injury, but may also be 
found on an otherwise uninjured surface. The fungus 
commonly attacks the older and weaker leaves first, but 
may spread from them to the younger ones. 

The disease may be confused with tip-burn or with 
arsenical or other injury to the foliage. The fungus 
may attack such injured or dead area first and later 
spread to healthy tissue. The spores are large, thick- 
walled, many-celled bodies produced on both surfaces of 
the older dead areas. The fungus is able to live over 
winter as a mycelium in the dead leaf tissue, and the spores 
themselves will remain alive for more than a year. They 
germinate in water, each cell being capable of sending 
out a germ-tube. These are able to enter the leaf through 
stomates or penetrate the epidermis directly. The 
fungus attacks the foliage only, but as a result of the 
attack the tubers may be small and thus the loss will be 
considerable. This will depend upon the virulence of 
the attack and may amount to one-half or more of the 
crop. 

The disease can be held in check by thorough appli- 
cations of bordeaux mixture. 



190 The Potato 

Late blight (Plate IX) 

Late blight, also known as downy mildew, is caused 
by the fungus Phytophthora infestans. It occurs in north- 
eastern United States and adjacent parts of Canada and 
sporadically farther south and on the Pacific Coast. It 
has also been known for years in many countries of Europe, 
and has been reported as occurring in Australia and in 
the high plateaus of South America where potatoes are 
grown. It prevails in those regions where the weather is 
relatively cool and moist, conditions most favorable for 
the growth of the potato itself, and, even there, is de- 
structive only during especially favorable seasons. For 
this reason the disease appears in epidemic form in 
many sections in occasional periods of years, the inter- 
vening periods being comparatively free from it. 

The disease shows on the leaves as water-soaked or 
brown areas that may occur on any part of the leaf. In 
moist weather these spots rapidly enlarge so that the 
entire leaf may become affected, and over the recently 
affected area, usually on the lower surface, a fine white 
mildewy growth may be noticed. The stem may be- 
come affected in a similar manner. In moist weather 
the affected areas soften instead of drying and give off a 
disagreeable odor characteristic of decaying vines. 

The fungus causing the late blight may attack the 
tubers (Plate IX), the upper surface of those lying nearest 
the surface of the soil being first infected, producing on 
them a discolored, water-soaked area which may be small 
or, if the soil is moist, may extend over much of the tuber. 
The affected area becomes somewhat sunken at digging 
time or later in storage and the flesh has a rusty-brown 
color. This condition is known as dry rot. The flesh 



Diseases of the Potato 191 

is not affected to a greater depth than one-fourth to one- 
half an inch, although such affected tubers in a heavy 
wet soil or even in storage may be invaded by saprophytic 
fungi or bacteria that produce a soft, malodorous condi- 
tion known as wet rot. 

The fungus causing late blight lives as a mycelium in or 
near the margin of the diseased area in affected tubers. 
When such tubers are planted under conditions favorable 
to the fungus, namely, a warm moist soil, the mycelium 
will grow into shoots often weakening them and some- 
times destroying them. 

When these affected sprouts succeed in growing, they 
appear above the ground as a slender, weak stalk often 
hidden by healthy neighboring ones from the same tuber. 
On these weak stalks the fungus, during moist weather, 
forms its fruiting bodies on which are produced a large 
number of spores. These are blown by air currents to 
neighboring healthy vines, where, if the vines are wet, 
they germinate in two to four hours in an interesting 
manner. An opening appears at the tip of the spore, 
and six or more zoospores are pushed out as naked masses 
of protoplasm that are able to move about in the water 
on the leaf surface by means of whip-like strands of 
protoplasm extending from their bodies. After moving 
about for an hour or so, they settle down on to the sur- 
face of the leaf and after a time send out a little tube, the 
germ-tube. The germ-tube is able, after a few hours, to 
penetrate the surface of the leaf. Once inside, the germ- 
tube grows rapidly into a mycelium extending between 
the cells and even penetrating them. These cells be- 
come disorganized and turn brown and from them the 
mycelium obtains its nourishment. Cell after cell is 
killed in this manner, and the discoloration resulting upon 



192 The Potato 

their death is noticed as a blighting of the leaf. After 
four or more days, the mycelium has produced fruiting 
bodies bearing more spores. These are carried by air 
currents or by other means to healthy leaves, which in 
turn become infected if the weather is wet, or they fall 
to the ground, where during rains they are washed into 
the soil. Thus under favorable weather conditions the 
fungus may spread from an infected vine to neighboring 
ones, causing them to blight, and thence to all the vines 
in the field until all are blighted. The spores, washed 
into the soil, come into contact with the new tubers and 
infect them in much the same manner as the leaves were 
infected, so that they rot in the manner described earlier. 
If the soil remains wet and soggy, as heavy soils often do 
during rainy periods of the fall, the fungus grows luxu- 
riantly in the tuber and produces fruiting bodies on its 
surface. Spores produced there infect other tubers in 
the hill and possibly spread to other hills. It has been 
shown that the fungus may fruit on the surface of the 
tuber in storage and infect mature tubers there, though 
this does not often happen. All that is necessary for 
infection of the tubers is the presence of spores on their 
surface under moist and fairly mild or cool weather. 
Infection readily occurs when the blighting vines come 
into contact with freshly dug tubers. These points are 
of importance, as it teaches us to leave blighting vines 
until they are dead and dry before digging unless we can 
dispose of the crop at once or unless there is danger of 
the tubers rotting badly in wet soil. Tubers infected 
shortly before digging time may show no evidence of it 
then, but the dry rot will appear later in storage. 

It has also been shown that throwing the soil over the 
tubers with a shovel plow to the depth of four or five 



Diseases of the Potato 193 

inches before or at the time the vines begin to blight will 
prevent a large amount of tuber infection. This method 
of control is a makeshift at best, and the practice in some 
localities is known to have reduced the yield. Spraying 
the soil with bordeaux mixture will aid in preventing 
infection of tubers, but usually is not practical. 

As the fungus grows best in the tubers under mild or 
moderately cool moist conditions, it naturally follows that 
infected tubers will rot but little or not at all when stored 
in a dry place and held at a low temperature (40° F. or 
below). The application of lime or formaldehyde to the 
tubers in storage is of no value in preventing rot. 

The disease, then, is caused by a fungus carried to the 
field with infected tubers. The fungus spores produced 
on infected vines spread readily during moist weather 
to the other vines in the field and to neighboring fields, 
producing blight whenever infection occurs. Many 
spores fall from the vines to the soil below and are washed 
to the tubers, which upon infection sooner or later show 
the dry rot. When the soil remains wet, such tubers 
become invaded by other soil fungi and bacteria which 
bring about a soft malodorous rot. 

As a result of many experiments it has been found that 
spraying the vines with bordeaux mixture is the best 
practical way to control the disease. Thorough appli- 
cations made frequently during the summer to keep the 
new growth covered, especially before rainy periods, and 
in the late summer and the early fall, will prevent infec- 
tion of the vines. If the vines do not blight, the tubers 
will not rot. More complete directions regarding spray- 
ing practices will be found under the chapter on Control 
Measures. 



194 The Potato 

Rhizoctoniose (Plates X and XII) 

This is a name given to the several symptoms of a 
disease caused by the fungus Rhizoctonia, which when 
producing its perfect spores is known as Corticum vagum 
var. solani. The fungus forms small black irregular 
masses often the size of a half-pea or smaller on the sur- 
face of the tuber. These resemble little chunks of muck, 
but can be readily detected by washing the tuber, for 
they do not wash off as soil does although they can be 
easily scraped off. These bodies, called sclerotia, enable 
the fungus to pass the winter without injury. In the 
spring, when planted with the tuber or even when kept 
in a moist place, a fine mycelium grows out from them. 
This attacks the sprouts and produces cankers on them, 
so that the portion above is commonly destroyed. 
Younger sprouts may then appear from below the can- 
kered area, but these in turn may be infected, so that the 
plants are late in making their appearance above the 
ground or do not appear at all. Affected plants that 
succeed in appearing may continue to grow and produce 
well. The fungus, however, commonly attacks and 
destroys the stolons and in this way reduces the yield. 
Older plants are sometimes weakened by cankers on the 
stems, and brown strands of mycelium may be observed 
over such affected areas. The cankers may be so severe 
that the vines become yellow in color and the leaves roll 
upward the same as when the vine is affected with black- 
leg. Indeed, in such cases the stem is sometimes found 
to be decayed by a black-rot similar to black-leg. Af- 
fected vines often have small aerial tubers formed in the 
axils of the leaves and the stems themselves are thick- 
ened. Such vines usually have a large number of small 




Plate X. — Potato diseases. Top, part of a potato leaf showing spots 

of early blight ; magnified. Bottom, rhizoctoniose. 

(Courtesy Dept. of Plant Pathology, College of Agriculture, Cornell University.) 



Diseases of the Potato 195 

tubers clustered close to the base. The fungus produces 
its spores, during moist weather on a thin, white, frost-like 
growth extending over the base of the stalks. 

This fungus is able to attack many kinds of plants and 
to live as a saprophyte in the soil from year to year. For 
this reason it is difficult, if not impossible, to eradicate it. 

The sclerotia on the tubers can be killed by soaking 
the tubers in corrosive sublimate solution, and if this 
treatment is coupled with a judicious rotation of crops 
on the land, the injury from the disease will be greatly 
reduced. 

Fusarium wilt 

This disease is caused by the fungus Fusarium oxy- 
sporum, which gains entrance through the roots from in- 
fected tubers or from the soil and works upward in sap 
vessels, interfering in that way with the normal circulation 
of the sap. The fungus mycelium destroys the roots and, 
later, fruits on them, producing abundant spores. The 
diseased condition of its roots and of the sap vessel causes 
a yellowing, dwarfing and finally a wilting and dying of 
the vines. The stem pulls up easily and its tissues beneath 
the outer layer have a light brownish color. This color 
in the vascular tissues extends to the roots, stolon, and 
tubers. A section across an affected tuber near the stem 
end shows a brown ring of sap vessels. This browning of 
the vascular ring is associated with some other diseases 
and is always found in tubers in which this Fusarium has 
developed to any extent, although in the earlier stages of 
infection no discoloration may be noticed. 
' Such diseased tubers should never be used for seed 
purposes, as vines coming from them nearly always be- 
come infected. The only successful way to control the 



196 The Potato 

disease is the selection of tubers from healthy plants and 
a wide rotation of crops as outlined under the chapter on 
Control Measures. 

Verticillium wilt 

This wilt is caused by the fungus Verticillium albo-atrum 
and shows symptoms much like the Fusarium wilt, and 
the two are very easily confused in the field. The fungus 
Verticillium gains entrance to the plant in much the same 
way and also inhabits the sap vessels of the plant. Af- 
fected plants show yellowing, wilting and dying of the 
leaves, beginning with the lower ones and progressing 
rapidly upward. The plants have a straggling appear- 
ance, usually die earlier than is normal and yield poorly. 
As with Fusarium wilt the tissues underlying the outer 
layers of cells show a brown discoloration, which in this 
case extends upwards into the branches as well as down- 
ward into the roots, stolons and tubers. The tubers 
show a blackened ring in a section of the stem end. The 
fungus passes the winter in such infected areas of the 
tuber and is also capable of living in the soil. The same 
methods of control should be practiced as for Fusarium 
wilt. 

Fusarium dry rot (Plate XI) 

This rot, caused by one or more species of Fusaria, is 
a dry rot extending deep into the tuber. The surface 
of the rotted area is much wrinkled and often shows 
numerous clusters of a white, moldy growth. The fun- 
gus gains entrance to the tuber through the skin wounds 
or through lesions caused by other fungi, so that the rot 
may occur at any point on the tuber. The powdery 
dry rot caused by Fusarium trichothecioides, common in 



Diseases of the Potato 197 

the western United States, "spreads rapidly in potatoes 
in transit to market or stored under unfavorable condi- 
tions." None of these dry rots is known to affect the vine 
to any extent. The fungi causing them will live in the 
soil and infect the new crop when an opportunity comes, 
so that in control all rotted tubers should be discarded 
for planting. 

Silver scurf 

This is caused by the fungus Spondylocladium atro- 
vire?is, recently introduced from Europe, and has been 
commonly observed in the United States. It shows as 
dark spots or areas on the surface of the tuber. In these 
areas fine black points are found which make up the spore- 
bearing area. The fungus destroys the skin so that the 
moisture escapes and the affected tuber shrinks badly. 
The affected areas at this time and even before have a 
silvery luster, a character which gives the disease its 
name. The market value of such tubers is lessened, and 
they should not be used for planting, as seed treatment 
is apparently ineffective in destroying the fungus. 

Potato wart 

This disease, caused by one of the lower forms of 
fungi called Synchitrium endobioticum, does not appear in 
the United States and should continue to be kept out by 
strict quarantine measures. The disease has been known 
in Hungary since 1896. It has been found in many 
European countries and also in Newfoundland. It is 
reported to be very destructive and is very difficult to 
control, a long rotation of crops being the only measure 
recommended. 



198 The Potato 

The fungus causing the disease gains entrance into the 
eyes, which become black and swollen. "In more ad- 
vanced stages one or more nodules, varying in size from 
that of a wrinkled pea to a lump as large or larger than 
the tuber itself, may be found. These are green where 
they project from the ground and white below, turning 
as they grow old to dark brown or almost black. They 
have a wrinkled coral-like appearance like the head of a 
cauliflower. 'A still more advanced stage occurs when 
the fungus has utilized every particle of food stored in 
the tuber and has reduced it to a brownish black soft 
mass, giving off a very unpleasant putrefactive odor.' 
Such potatoes cannot be harvested whole. The black 
pulpy mass breaks up, liberating millions of sporangia 
(spore-sacs) which live for years in the soil. These 
sporangia have been known to infect potato crops after 
an eight-year interval." l 

Common scab 

Common scab, caused by a soil bacterium, Actinomyces 
chromogenas, is too well known to require detailed de- 
scriptions. The organism affects only the outer layers of 
cells, though there are deep scabs supposed by some to 
be caused by the same organism. It has been shown 
that gnats and possibly other insects may be responsible 
for the original deeper injury, though the scab may also 
be present. 

The scab organism winters over on the scabby tuber, but 
may also live from year to year in the soil. Badly scabbed 
tubers should not be planted. Clean tubers, as well as 
those not badly scabbed, after being treated may be 

1 U. S. D. A., Farmers' Bui. 489. 




Plate XII. — Spindling potato sprouts ; upper picture, the disease 

rhizoctiniose. 

(Courtesy Dept. of Plant Pathology, College of Agriculture, Cornell University.) 



Diseases of the Potato 199 

planted on land where crops have been rotated. Lime, 
wood ashes, manure and other materials giving alkaline 
reaction should not ordinarily be used on potato soil in 
connection with the growing of that crop. If it is neces- 
sary to apply any of these substances in order to grow 
other crops the application should be made in the fall 
after digging the potatoes. Manure may be applied best 
as a top dressing to the, meadow. 

Black-leg 

This disease, which is caused by the bacterium Bacillus 
phytophorus, affects the vines and tubers. Infected 
vines have a lighter green color than is usual and have a 
stiff upright growth instead of the normal spread of foli- 
age. The leaflets have a tendency to roll about the mid- 
rib. The plant also may be smaller than it would natu- 
rally be, though this is not always so. The base of the 
stem is quite black and somewhat shriveled. The 
diseased area commonly extends two or three inches 
above the ground, sometimes much farther. It also 
extends downward to the old seed tuber and may extend 
into the stolons and young tubers. 

The affected tubers may show a stem-end black-rot, 
and when cut lengthwise sometimes show a black, foul- 
smelling center decay and even a hollowed condition. 
This center decay may be present with little evidence of 
it at the surface. 

The disease is distributed mainly by affected seed 
tubers, or by bruised, cracked or decayed tubers harbor- 
ing the organism. Control consists in the selection of 
seed tubers from healthy plants, in discarding bruised, 
cracked and rotted tubers, and in seed treatment. 






200 The Potato 

Bacterial wilt 

Bacterial wilt, caused by the bacterium Bacillus 
solanacearwn, is a disease that affects potatoes, tomatoes, 
eggplants and a few other solanaceous plants. It occurs 
mostly in the southern United States. The vines wilt sud- 
denly, often on a single stalk, but later affecting the entire 
plant. The stems lose their bright green color and be- 
come shriveled and blackened. The vascular tissues, at 
an early stage, have a brown color somewhat similar to 
that described for Fusarium wilt. This color can be 
seen through the outer cells and extends upward as nar- 
row black streaks, even out upon the leaf petioles and 
vines. When such stems are cut across, tiny drops of 
liquid ooze out of the vessels at the cut surface. These 
are of a dirty or yellowish white color, but not sticky or 
foul smelling. Examination with a microscope shows 
them to be swarming with bacteria. 

This discoloration of the stem extends downward into 
the stolons and tubers. A section across an infected 
tuber at the stem end usually shows a blackening of 
vessels, making a dark ring around the cut surface of the 
tuber near the periphery. Bacteria similar to those 
found in the stem are present in these vessels of the tuber 
and later invade the other tissues, finally rotting the 
entire inside of the tuber. 

The bacillus is carried from infected to healthy plants 
by insects that infest the potato vines. Probably this 
is the common means of dissemination. Control, there- 
fore, would consist in destroying the insects as far as 
possible and in the early removal of infected plants from 
the field. 



Diseases of the Potato 201 

Powdery scab (Plate XI) 

Powdery scab is a disease of the tuber which is caused 
by a slime-mold, Spongospora subterranea. It may be 
easily observed at an early stage in young tubers as 
brownish colored blisters. These, later, show as pits 
filled with a brown powder, the spores of the parasite. 
These pits are bordered by the torn skin of the tuber. 
In storage the slime-mold may continue to be active, 
causing a dry sunken rot about the pit. A cankerous 
stage of the disease has been described as occurring in 
low, wet lands, in which case the deeper tissues of the 
tuber are invaded by the slime-mold and by other organ- 
isms, so that it becomes badly rotted. The disease has 
not been serious in the United States, and its develop- 
ment seems to be arrested in the warmer potato sections. 

The parasite is disseminated by the distribution of 
affected tubers and by any agent upon which the spores 
may become lodged. The disease is difficult to control, 
but it is said to be materially reduced by seed treatment 
and rotation of crops. Affected tubers should be de- 
stroyed by burning or by boiling, and no tubers, even 
though healthy, coming from fields known to be infested 
should be used for planting. 

Tip-burn 

This is a disease characterized by a browning and 
shriveling of the tips and margins of the leaves. The 
trouble may become quite severe and greatly reduce 
the yield of tubers. It is often confused with blight, but 
it is not due to parasites, but to hot, dry weather follow- 
ing a period when the conditions of temperature and 



202 The Potato 

moisture favored a rapid growth of the vines. Cultural 
practices that aid in the conservation of moisture com- 
bined with frequent applications of bordeaux mixture 
will reduce the amount of leaf -area injured. 

Arsenical injury 

This is a burning caused by a heavy application of 
paris green or other insecticides containing free arsenious 
acid. The injury often resembles early blight, but is 
lighter colored and usually occurs about flea-beetle punc- 
tures or other injuries to the leaf, while early blight spots 
may occur on the otherwise uninjured leaf. The neces- 
sary amount of the more caustic poisons used with bor- 
deaux mixture or with equal parts of lime should cause no 
burning. 

Spindling sprout (Plate XII) 

Spindling sprout is a disease characterized by very 
small, weak, needle-like sprouts coming from the eyes 
instead of large vigorous ones. Vines from such sprouts 
remain small and weak and only small unmarketable 
tubers are produced from such hills. It is believed that 
tubers becoming unduly heated by the hot soil during 
their growth produce sprouts of this character. If this 
is true, northern-grown seed is less likely to be affected. 

Net necrosis 

This name is applied to a diseased condition of tubers in 
which brown streaks occur within the tuber. These 
streaks are confined largely to the vascular system, though 
they do not appear as a dark ring on the surface of a cut 
across the tuber as is usually the case with other vascular 



Diseases of the Potato 203 

diseases, but they may also be found within the central 
area of the cut surface. They may be found throughout 
the length of the tuber or be confined to the stem end. 
The exterior appearance of the tuber gives but little 
indication of conditions within. The vines also become 
affected, but the symptoms have not been studied care- 
fully enough to differentiate them from those of wilt 
disease. No organism has been found associated with 
the streaks in the tubers, but an organism has been found 
associated with affected stems and roots. Affected tubers 
should be discarded for planting as they may produce 
weak plants, but they are not unfit for food. The same 
or a similar disease is known in England as "Sprain" 
and in Germany as " Eisenfleckigkeit." 

Curly dwarf 

Curly dwarf is a non-parasitic disease characterized 
by a wrinkling and curling of the leaf-blade about the 
veins and midribs. Affected plants are usually dwarfed 
and die earlier than healthy ones, though all stages of the 
disease may exist in a field, and in some plants it may be 
so slight as to be hardly noticed. The yield in advanced 
cases is very much reduced. Tubers from affected 
plants, while they show no evidence of disease when 
planted, will produce vines that show a more advanced 
stage of the disease. Since the presence of the disease 
is partly responsible for reduced yields, no tubers from 
affected vines should be planted. The elimination of 
these can best be accomplished by inspection of the 
vines in the field about blossoming time of the plant, at 
which time affected hills should be removed or marked 
for removal. 



204 The Potato 

Mosaic 

This disease is characterized by a crinkling of the 
foliage and by a mottled condition due to numerous small 
areas of the leaf-blade having a lighter green color than 
is usual. In some plants this is not especially notice- 
able, for there are all gradations from healthy plants to 
badly diseased ones. The disease is more commonly 
found on white sprout varieties and is said to reduce the 
yield materially. Since, like curly dwarf, it is transmitted 
by means of the tuber, the same selection should be prac- 
ticed. 

Leaf -roll 

Leaf-roll is the name given to a non-parasitic disease 
of the plant and is characterized by a dwarfing and a 
yellowing of the vines and by an upward rolling of the 
leaflets about their midrib. The leaves have a tendency 
to point upward and are rather stiff to the touch. There 
are. perhaps, several types of the disease. In one type 
the lower leaves at first show a tendency to roll and be 
stiff though the plant is otherwise normal in appearance. 
In another type the foliage has a yellowish cast. The 
leaflets of the upper and younger leaves point upward 
and roll and often show a rose or light purple color at the 
lower margins. There are all gradations of the disease. 
and the well-marked types show great reduction of growth 
and yield. The disease is transmitted by means of the 
tubers, so that rigid selection in the field is necessary to 
avoid it. 

The cause of curly-dwarf, mosaic and leaf-roll is un- 
known. Many theories have been advanced to explain 
them, but it is unnecessary to discuss them here. All 



Diseases of the Potato 205 

three diseases are evidently widespread and may be 
important factors in causing reduced yields and "running 
out" of potatoes. Tubers from such vines are usually 
small. For this reason the selection of small tubers from 
the bin is likely to increase the percentage of such affected 
plants. It is possible to avoid them by the selection out- 
lined in the chapter on Control Measures. 

Constitutional degeneracy and other weakened conditions 
of plants 

Constitutional degeneracy is a name given to a condi- 
tion of weakness of growth showing as small, often spin- 
dling stems producing but a few small tubers to a hill. 
Such a condition is inherent in the plant and is inherited 
by the progeny. This trouble may be confused with 
similar conditions associated with the non-parasitic 
diseases already enumerated. Very small, spindling 
plants producing no commercial tubers are often found 
to be associated with an early rotting of the seed tuber 
after being planted, and similar plants sometimes appear 
when the only eye on the piece of tuber is near the cut 
surface. Rotting of tubers may be due to such prac- 
tices as keeping cut tubers undusted a week or more 
before planting and as planting cut tubers in hot soil or 
leaving them exposed to the sun after hand-planting. 
Avoiding such practices may be of assistance in reducing 
the number of weak plants in the field, but tubers from 
degenerate hills should never be used for seed. The 
elimination of these can be accomplished to some extent 
by grading, but selection from the field is the surest way. 



CHAPTER XI 

CONTROL MEASURES AGAINST DISEASES 
By M. F. Barrus 

It will be noticed from reading the preceding pages 
that for some diseases the selection of seed tubers is 
advised and for others seed treatment, crop rotation or 
spraying is recommended. It may be necessary to prac- 
tice more than one control measure in order to control 
some diseases. For the seed potato grower, it is desirable 
and is becoming more and more necessary that all meas- 
ures be employed that will tend to produce sound tubers 
free from all diseases. Detailed directions for carrying 
out these measures are given in these pages. 

Control of curly-dwarf, mosaic and leaf -roll 

As has already been pointed out, such diseases as curly- 
dwarf, mosaic and leaf-roll, transmitted by the tubers, 
cannot be detected by the appearance of the tuber out- 
side or within. There is very little or no outward evi- 
dence on tubers affected with Fusarium and Verticillium 
wilt, bacterial wilt and net necrosis, and occasionally on 
some tubers affected with black-leg. Even a section of 
the stem end will sometimes fail to reveal the presence 
of these last-named diseases. In such cases, it is very 

206 



Control Measures 207 

necessary, if these diseases are to be avoided, to inspect 
the field one or more times during the growing season in 
order to detect the affected hills from the appearance of 
the vines. If only one inspection can be given, this should 
be made at about the blossoming time, because the non- 
parasitic and other troubles can be best detected at this 
time. A second inspection before the vines die will often 
reveal diseased vines that could not be seen earlier. At 
the time of inspection all diseased hills should be marked 
for removal before digging the others in order that they 
may not be mixed with them. If there is a considerably 
large percentage of them, more than 10 or 15 per cent, 
the crop should not be used for commercial seed purposes. 
The grower, however, may select from such a field plants 
that are healthy for his own seed, and these should be dug 
before the others and stored by themselves. 

Field inspection 

The grower may feel that he is unqualified to do such 
inspection himself, but certainly he can detect poor hills, 
and with a little instruction from an expert can learn to 
distinguish the various diseases. If, however, individual 
farmers growing seed potatoes for sale make their own 
inspections, there will be a great diversity of standards, 
hence it is more practical for one man to inspect all the 
fields in a certain locality. Such a man should be trained 
for the work. He may be employed by an association of 
potato-growers or by some other organization, or he may 
be an official inspector of the state or country employed 
to inspect fields, and tubers after digging, for the purpose 
of certifying them. Some such method will greatly im- 
prove the seed stock, and the grower of such stock will 



208 The Potato 

not only be able to secure better prices, but will increase 
his own yields because of the use of better seed. The 
time will not be long before the southern potato-grower 
will demand seed tubers certified by some responsible 
organization, and poor seed will find a market for table 
stock or some other purpose. 

Not all the vines thought to be healthy in the field will 
produce satisfactory seed tubers. There may be hills 
among them that produce a small number of marketable 
tubers, and these should be eliminated from seed stock, if 
possible. However, this can be done only by digging 
each hill separately and selecting tubers from desirable 
hills, as explained in an earlier chapter. Growers should 
do this whenever possible to improve their own seed, but, 
to improve further the seed stock for sale, much can be 
done by grading because of the small tubers, many of which 
come from weak or diseased hills. Growers at planting 
time should discard all rotted, bruised or badly scabbed 
tubers, for these are not as satisfactory as healthy, smooth 
ones, even when treated. 

Seed treatment to prevent disease 

Seed treatment as directed will destroy organisms living 
on or anchored on the surface of the tuber. For this 
reason, it is to be advised when such diseases as com- 
mon scab, powdery scab, rhizoctoniose and black-leg are 
troublesome. Treated tubers often give a better stand 
because rot organisms, ordinarily saprophytic, found on 
the surface of the tuber are destroyed. Treating the 
seed also eliminates the danger of introducing disease 
organisms into new soil or soil that has been freed from 
them to a greater or less extent. Few growers have 



Control Measures 209 

believed that these organisms introduced with the seed 
affect not only the crop of that year but remain in the 
soil to attack subsequent crops of the same or other kinds. 

Treating seed tubers is not as troublesome as some 
farmers think. The treatment, if desired, can be made 
several weeks in advance of planting, but less handling is 
necessary if it is made immediately before cutting. Where 
one has only one hundred bushels or less to be treated, it 
is convenient to place two or more barrels on a platform, 
which should be high enough to draw the solution off 
through a hole near the bottom of the barrel. The pota- 
toes are dumped into the barrels and are covered with 
the solution, which may have been prepared in another 
barrel. One barrel of solution will cover two barrels of 
potatoes. After they have soaked the required length of 
time, the solution may be drawn off at the bottom and 
emptied into the barrel in which it was prepared. The 
treated tubers can now be emptied on to the ground to be 
dried, but care should be taken that they are not over- 
heated by the sun. The barrels can be filled again with 
potatoes and the same solution used once more. While 
waiting for this lot to soak the tubers already treated 
may be cut for planting. This saves time. By using 
two barrels, it is possible for one man to treat about 50 
bushels of potatoes in a day and have time to cut tubers 
for planting between treatments. Two men can treat 
about 250 bushels in one day by the use of 10 barrels 
in making the treatment. 

Either formaldehyde or corrosive sublimate may be 
used. The former is much cheaper, less poisonous and 
can be used in metal vessels if desired, but it is not as 
effective in destroying the sclerotia of Rhizoctonia as cor- 
rosive sublimate. A pint or pound of 40 per cent form- 



210 The Potato 

aldehyde, costing about 30 cents, should be diluted with 
30 gallons of water. This can be used over and over 
again for at least ten times without losing strength, but 
the quantity will, of course, be diminished with each treat- 
ment. The tubers should be soaked in it for two hours. 
A longer time may injure the sprouting power of the tuber. 
When corrosive sublimate is used, four ounces of the dry 
powder, costing about 50 cents, should be used to 30 
gallons of water. The powder should first be dissolved 
in a quart or two of warm water and then added to the 
other. It dissolves more slowly in cold water. The solu- 
tion should not come in contact with metal, as it reacts 
with it and loses strength. Neither should it be used 
more than three times in treating potatoes unless renewed 
with fresh solution, for it loses its strength rapidly with 
use. Tubers should be soaked in it for at least one and 
one-half hours, but never longer than five hours. Great 
care should be taken in its use, for it is exceedingly poison- 
ous. Treated tubers should never be used as food. 

Where one has large quantities of tubers to be disin- 
fected at one time, the formaldehyde gas treatment may 
be used. For this purpose the tubers should be placed in 
crates or in shallow slatted bins so as to permit the free 
movement of gas about them. The disinfecting room 
should be made as air-tight as possible. Spread potas- 
sium permanganate evenly over the bottom of a large 
deep pan or bucket. Twenty-three ounces should be 
used for each 1000 cubic feet of space within the room. 
Pour over the permanganate three pints of 40 per cent 
formaldehyde for each 1000 feet of space. Give the pan 
a tilt, leave the room as quickly as possible, and close the 
door tightly, leaving it closed for 24 hours or, at least, over 
night. The door can then be opened and the room aired 



Control Measures 211 

out, after which the potatoes may be handled as any 
other treated tubers. The following recommendations 
should be observed by those using this method. Make 
the treatment before the potatoes sprout. Place the 
generating pan so that no potatoes are within three feet 
of it and none directly above it. Use at least 167 bushels 
of potatoes for each 1000 cubic feet of space or injury 
will result to the tubers. This injury shows as a pitting 
about the lenticels. Do not attempt treatment when the 
temperature of the room is below 50° F. It is most 
affective at 80° F. Thoroughly wet the floor of the dis- 
infecting room with boiling water just before adding the 
formaldehyde to the permanganate, as moisture in the air 
of the room is very essential for effective work. Do not 
attempt to treat potatoes in sacks or piled high in bins. 

The question often arises as to whether the crates or 
bags in which the tubers are to be carried to the field 
should be sterilized or whether cutting-knives should be 
often disinfected. It is possible for spores of the organ- 
isms causing potato diseases to be carried on containers 
or implements and later come in contact with the tuber 
under such conditions that infection may take place. 
The writer is of the opinion that infection in this manner 
does not frequently take place, but if one desires to avoid 
every possible contamination, this disinfection will be 
necessary. It may even be desirable when such diseases 
have been very troublesome, but ordinarily it is not neces- 
sary, although one should use judgment in the matter. 

If potatoes are cut more than a few days in advance of 
planting, they should be dusted to prevent decay from 
the action of saprophytic bacteria under favorable con- 
ditions of heat and moisture. While other kinds of dust 
will prevent the decay, flowers of sulphur is preferable as 



212 The Potato 

it has fungicidal properties. Indeed, it has been shown 
that when sulphur is used in sufficient quantities, it aids in 
the reduction of powdery and common scab. Gypsum 
makes a satisfactory material for dusting, but lime in any 
form should not be used for this purpose as it may induce 
scab. 

Disease from organisms already in soil 

It must be remembered that seed treatment, while it 
destroys certain pathogenic organisms on the surface of 
the tuber, does not insure immunity of the crop from these 
diseases. Many of these organisms also live in the soil 
from year to year, and these are as able to attack plants 
coming from treated as from the untreated seed. The 
treated seed must be planted in soil that is free from these 
organisms or where they are much reduced or in an in- 
active condition. It is impractical to sterilize soil for 
growing potatoes, although for greenhouse and other 
valuable crops it is considered to be a good practice. 
The application of chemicals to the soil that will destroy 
or retard the growth of these organisms has not given 
very satisfactory results. Sulphur applied at the rate of 
450 to 900 pounds to the acre has reduced the amount of 
scabby tubers to a considerable extent, but it may also 
reduce the yield. It has been observed that clover will 
not grow in soil treated in this way. Fertilizers such 
as lime, which increase the alkalinity of the soil, greatly 
favor the development of scab, while acid phosphate, sul- 
phate of ammonia and the like, at least, do not increase 
scab injuries. 

When potatoes are grown year after year upon the 
same land, the parasites, especially those that live in the 
soil, are likely to increase unless one constantly guards 



Control Measures 213 

against them. On the other hand, if the potato crop is 
alternated with other crops or can be grown in a three- 
to five-year rotation, these parasites depending upon the 
potato for food will be starved out during the intervening 
years. Unless such parasites are introduced again by 
planting affected seed, or with manure containing these 
organisms, or with infected soil washed or carried on to 
the land, the potato crop planted in a rotation should be 
comparatively free from them. 

This would be the case were it not the habits of some 
organisms like Rhizoctonia to live on hosts other than 
the potato, or of others like the scab organism to live 
from year to year on dead organic matter in the soil. 
However, a rotation aids in reducing these organisms 
when they are troublesome, and for this reason, if for no 
other, should be practiced when possible. 

Often there are a large number of missing hills in a 
field caused by the decay of the seed tuber from attacks 
of Rhizoctonia, or for other reasons, causing the total 
yield to be materially reduced. This is especially true 
when the tubers are planted in hills or at distances greater 
than 18 inches in the row. When the tubers are planted 
close together, a missing hill does not mean a complete 
loss, because the neighboring hills, having more room for 
growth, will produce a larger yield. Some farmers have 
found it profitable to replant missing hills with tubers 
that have been greened, i.e. left in the light so that they 
have stubby green sprouts. Such tubers when planted grow 
rapidly and are not much later than the ones planted first 
and not greened. Greening potatoes is a good practice, for 
such tubers will give a better stand than those not greened. 

There are diseases, such as early and late blight, that 
occur under favorable weather conditions and do much 



214 The Potato 

damage even though the seed has been carefully selected 
and treated and other precautions taken. 

Treatment for potato blight 

The blight-rot fungus is not destroyed by seed treat- 
ment, and slightly affected tubers may be overlooked in 
sorting. Blight spores, being easily carried by air cur- 
rents, are readily disseminated from one field to another 
and bring about an infection if wet weather prevails. It 
must be remembered that the tubers are infected by 
spores produced on blighting vines. Hence, to prevent 
this rot from occurring, it is necessary only to prevent 
the vines from blighting. The vines will not blight, even 
under very favorable weather conditions, if the spores do 
not gain entrance into their tissues. The spores cannot 
enter the leaves if the vines are thoroughly sprayed with 
bordeaux mixture before the spores have germinated. 
As they germinate only in the presence of moisture, the 
applications need be made only before moist conditions 
prevail, that is, before rainy periods. "The grower should 
not hesitate to spray at such times for fear that the mix- 
ture will be washed off. It dries rapidly, and once dried 
on the vines, enough remains even after heavy rains to 
protect them from the fungus." 

Every susceptible part of the vines should be protected 
by the mixture. To do this effectively, it is necessary 
that the mixture should come from the nozzle as a fine 
mist and settle over every leaf and stem like a fog. Such 
a mist can be produced with a satisfactory nozzle and 
with good pressure. 

One application thoroughly done will protect the parts 
receiving it for a long time, but new leaves appear, and 



Control Measures 215 

these must be protected by subsequent applications. 
These applications should be continued as long as growth 
of the vine takes place. Even when the vines cover the 
space between the rows and driving through will injure 
them, the spraying must be done. Less loss will result 
from injured vines than from rotted tubers. On loamy 
ground, the injury to the vines is not so great as one would 
think. Some ingenious farmers have devised a means of 
pushing the vines away from the wheels by attaching rake 
teeth on each side of each wheel. Manufacturers of 
spraying machinery should be able to devise some means 
of overcoming this objection to spraying. 

From five to eight applications, depending upon weather 
conditions, should be made during the season. The first 
should be given when the plants are six to eight inches 
high or when a poison is applied to kill the bugs. For 
the early applications 50 to 75 gallons of mixture to the 
acre will be sufficient, but later in the season it will re- 
quire 100 gallons or more. Enough should be applied to 
do a good piece of work even though it takes 150 gallons. 
The operator should determine this. Nozzles capable of 
delivering this amount of liquid as a mist must be the 
only kind employed, although pressure has much to do 
with fineness of the mist. From 70 to 80 pounds of 
pressure will make a fine mist with vermorel nozzles if 
there are not too many used at a time, while it will take 
100 to 150 pounds of pressure to get a good mist with an 
equal number of disk nozzles. But the vermorels do not 
have the capacity that disk nozzles do and more are re- 
quired to do the same work. One disk nozzle will do 
good work at first, but two should be employed later on 
and then should be so adjusted that the spray is directed 
at an angle rather than straight down upon them. The 



216 The Potato 

pump of the machine should be capable of maintaining a 
uniformly high pressure. These are factors that must be 
considered in buying or constructing a machine. Other 
points are of secondary importance. For small fields of 
an acre or less, a small compressed air spray may be used. 

The operator should see that the mixture gets on to the 
vines. It is of little value applied to the soil. It occa- 
sionally happens that a nozzle becomes clogged, and the 
vines below are not being properly sprayed. One cannot 
hope to spray a field adequately by merely driving through 
it. Much depends on the interest taken by the driver. 
One can best determine whether the application is thorough 
by examining the vines after spraying them. 

Various strengths of bordeaux mixture have been 
recommended. The 5 : 5 : 50 formula is commonly used 
on potatoes. Experiments have shown that the spores 
of the blight fungus can be prevented from germinating 
at a much weaker strength, so that there is little doubt 
that the blight can be controlled with bordeaux mixture 
at 2 : 2 : 50 or 3 : 3 : 50. When copper sulphate is very 
expensive, as at present, larger profit can doubtless be 
secured with a weaker mixture than with a stronger one, 
which may give slightly increased yields from greater 
stimulation. 

For many years potato spraying experiments have 
been conducted in several states. The bordeaux mix- 
ture has been prepared in various ways, and used at 
different strengths. The experiments have been con- 
ducted on experiment station grounds and on farms in 
various parts of the country. These applications have 
been made by scientific men and by farmers with hand 
machines and with traction sprayers. The conclusion in 
nearly every case has been that it pays to spray with 



Control Measures 217 

bordeaux. There have been years when certain fields 
have shown no increase from spraying, but usually a suffi- 
cient increase has been obtained, if the spraying has been 
well done, to pay for the cost of the applications. Even 
in years when the blight is absent, the application of bor- 
deaux appears to stimulate the vines, for they are greener 
and remain alive longer than unsprayed vines. Bordeaux 
also acts as a repellant to the flea-beetle and reduces the 
amount of tip-burn and so protects the leaves from vari- 
ous injuries. In years when blight is present, the evi- 
dence is greatly in favor of spraying. One cannot tell 
with any certainty when blight will come, so one should 
practice spraying as a protection. Growers should accept 
the evidence and make spraying of potatoes with bordeaux 
a general farm practice every year whether wet or dry on 
both early and late varieties. 

Preparation of bordeaux mixture (See Plate XIII) 

Bordeaux mixture can be purchased on the market as 
a paste or powder. Usually most of the proprietary mix- 
tures contain in addition an arsenical poison for killing 
biting insects. They are prepared for spraying by the 
simple addition of water to a given quantity of material. 
For this reason they are convenient to use and also safer 
when one needs to depend on irresponsible help to do the 
work. However, these do not stay in suspension as well 
as bordeaux properly made at home, and they are more 
expensive. Home-made bordeaux, according to most 
comparative experiments, is the most satisfactory. Its 
preparation is easy and inexpensive and one requires but 
a short time, when the apparatus for making it is once 
constructed. The following directions with a few addi- 



218 The Potato 

tions are taken from the New York Cornell Agricultural 
Experiment Station, Circ. 19, 1913. 

The best bordeaux mixture is made by mixing a dilute 
solution of copper sulphate (blue vitrol) with a dilute milk- 
of-lime. The mixture may be made of various strengths 
by using different amounts of copper sulphate and lime to 
a given amount of water. A combination of 3 pounds 
of copper sulphate and 3 pounds of lime to 50 gallons 
of water is probably strong enough to control the blight, 
but because of the stimulating action of bordeaux mixture 
on the potato plant, a strength of 5 pounds each of 
copper sulphate and lime to 50 gallons of water is usually 
recommended. This is indicated by the formula 5 : 5 : 50. 
In order to make the bordeaux mixture of any strength, 
the procedure should be as follows : — 

A stock solution of copper sulphate should be made in a 
barrel from 45 pounds of copper sulphate dissolved in 45 
gallons of water. A gallon of the solution will then con- 
tain about one pound of copper sulphate. If the crystals, 
placed in a gunny sack, are suspended so as to be slightly 
beneath the surface of the water, they will dissolve in 
three or four hours. 

A stock mixture of lime should be made from a bushel 
of good stone lime placed in a barrel and slaked by the 
gradual addition of water. Care must be taken not to 
"drown" the lime. When it has become pulverized by 
the slaking, water is added to make a paste, and then 
enough more water may be added to make 45 gallons. 
This should not be allowed to dry out. Hydrated lime 
(which is already slaked) may be used in place of stone 
lime, but air-slaked lime should never be used. 

Another barrel or larger container or even the sprayer 
tank itself may be used for mixing the bordeaux. What- 



Control Measures 219 

ever container is used should be filled three-fourths full 
of water. If a 5 : 5 : 50 solution is desired, 5 gallons of 
copper sulphate stock solution should be added to this 
water for every 50 gallons of mixture to be made. The 
solution requires stirring until it is well diluted, after 
which 5 gallons of the stock mixture of milk-of-lime should 
be added to each 50 gallons of mixture. The lime-water 
should be run through a strainer in order to prevent the 
larger particles of lime from getting into the sprayer tank. 
While the milk-of-lime is being added to the dilute copper 
sulphate solution in the sprayer tank, the material in the 
container should be stirred constantly. The sky-blue 
bordeaux mixture will result. Enough water to make the 
required amount of mixture must be added to it. 

It is often more convenient, although not necessary, to 
make the bordeaux on an elevated platform so as to allow 
the mixture to run by gravity into the sprayer tank (see 
Plate XIII). When such a platform is provided, it is easily 
possible to dilute both the stock copper sulphate solution 
and the stock lime solution in separate containers before 
mixing them by allowing them to run together. This 
method makes a bordeaux that stays in suspension a little 
better than that made by diluting but one stock before 
mixing. In case the latter method is used the required 
amount of stock in each case should be diluted with one- 
half the amount of water necessary to make the mixture. 

The mixture should now be tested with a few drops 
of a solution of potassium ferrocyanide. This is made 
from crystals of potassium ferrocyanide dissolved in soft 
water. Five cents' worth of crystals dissolved in a pint of 
water will provide enough of the solution to last through- 
out the season. Should a brown precipitate result when 
a few drops of this solution are added to the bordeaux 



220 The Potato 

mixture, it would indicate that more lime-milk is needed 
to neutralize the copper sulphate solution. When suffi- 
cient lime is added, no brown precipitate will be formed 
by the potassium ferrocyanide solution. Bordeaux mix- 
ture will burn the foliage of plants if it is not properly 
neutralized. It is unnecessary to measure the milk-of- 
lime in making bordeaux mixture if the mixture is tested 
from time to time with the ferrocyanide solution while 
adding the lime. The test will indicate when sufficient 
lime is present. 

When it is necessary to spray with a poison in order 
to kill potato beetles and other biting insects, the re- 
quired amount of poison may be added to the bordeaux 
mixture. 

Other remedies 

Soda bordeaux, in which an equal amount of sal-soda is 
used in place of lime, has been employed by some potato- 
growers, but carefully conducted experiments indicate 
that other preparations with copper compounds are in- 
ferior to lime. Dry bordeaux applied as a dust has not 
proved to be a satisfactory fungicide. Lime sulphur solu- 
tion is also unsatisfactory and unsafe. Where it has 
been used in experimental work, potato plants sprayed 
with it have given smaller yields than the unsprayed ones. 
Powdered sulphur and arsenate of lead or arsenate of zinc 
have been tried in New Jersey on early potatoes, but have 
been found to be less satisfactory and more expensive 
than bordeaux mixture. 

Fusarium dry rot and other rots are caused by organ- 
isms that gain entrance to the tuber through wounds. 
Potatoes with tender skin loaded into cars in hot weather 
soon after digging often rot badly. Care in handling the 



Control Measures 221 

tubers is necessary if one wishes to avoid these troubles. 
Provisions for ventilation should be made when the tubers 
are placed in storage. A potato tuber contains living 
protoplasm which gives off carbon dioxide, water and 
a certain amount of heat, and when provision is not made 
for ventilation, black-heart or center decay may occur. 

Disease-resistant varieties 

These various control measures have been discussed 
because it is necessary to adopt some or all of them if one 
is to grow healthy tubers. However, each practice adds 
to the cost of producing the crop. If such measures do 
not increase the yield or add to the value of the tubers, 
they are not worth putting into practice. If it were pos- 
sible to obtain potatoes that would not become diseased 
even when subjected to the parasite under favorable con- 
ditions for infection, much labor and expense would be 
saved. It is well known that certain individual plants as 
well as animals have shown marked resistance to diseases 
that ordinarily occur on their kind. By selection and 
breeding, it has been possible to obtain highly resistant 
plants producing crops of good quality. Notable ex- 
amples are wilt-resistant melons, cotton and flax, rust- 
resistant wheat and anthracnose-resistant beans. For 
several years scientists have been endeavoring to secure 
a satisfactory strain or variety of potatoes that is blight 
resistant. Some varieties have been secured that have 
shown a fair degree of resistance to blight or rot. Unfor- 
tunately, a variety that seems to show a slight degree of 
resistance to blight may show considerable susceptibility 
to rot, and varieties showing resistance to early blight 
may be subject to late blight. William Stuart of the 



222 The Potato 

Department of Agriculture, Washington, D. C, has 
reported certain varieties that have shown considerable 
resistance to both early and late blight. These are 
Apollo, Sophia, Professor Wohltman and Max Eyth. 
They are all foreign varieties and under conditions of 
climate and soil in the United States they succeed very 
poorly, being light yielders and rather poor in quality. 
Stuart remarks that it would seem as if high disease- 
resistance of the vine was correlated with low yield and 
undesirable tubers. He found no varieties tested to have 
strongly marked scab-resistant qualities when grown in 
soil well infested with the scab organisms. He believes 
that the value of disease-resistant varieties is problem- 
atical, but that the plant-breeder, by mating them with 
the most desirable commercial American types, may 
develop commercial types of resistant varieties. 

Summary 

It may be well to summarize control measures in the 
following way : — 

What selection does. — It aids in eliminating curly- 
dwarf, leaf-roll, mosaic, the various wilts, black-leg and 
other diseases showing on the vines and also transmitted 
by the tuber. It eliminates low-yielding hills. It elimi- 
nates impurities in a variety. 

What seed treatment and rotation do. — They reduce in- 
jury from rhizoctoniose, scabs and black-leg. They 
increase the stand of potatoes in the field.' They give 
clean tubers. 

What spraying does. — It prevents early and late 
blight. It prevents the blight rot. It reduces injury 
from tip-burn. It repels flea-beetles. It kills the bugs. 



Control Measures 223 

It stimulates the vines to longer periods of growth. It 
gives increased yields. 



REFERENCES 
Duggar, B. M. 

1909. Fungous Diseases of Plants. (Ginn & Co.), 1-508, Figs. 
1-240. 
Gloyer, W. O. 

1913. The Efficiency of Formaldehyde in the Treatment of Seed 

Potatoes for Rhizoctonia. New York (Geneva) Agri. 

Expt. Sta. Bui. 370 : 417-431, pi. 1. . 
Jones, L. R. 

1899. Certain Potato Diseases and Their Remedies. Vt. Agri. 

Expt. Sta. Bui. 72 : 3-32, Figs. 1-17. 
Jones, L. R., Giddings, N. J., and Lutman, B. F. 

1912. Investigations of the Potato Fungus. Phytophthora 

Infestans. U. S. D. A., Bur. PL Ind., Bui. 245 : 5-100, 

Figs. 1-10. 
Lutman, B. F. 

1911. Twenty Years Potato Spraying for Potato Disease. 

Potato Diseases and the Weather. Vt. Agri. Expt. 

Sta. Bui. 159 : 215-296. 
Lutman, B. F., and Cunningham, G. C. 

1914. Potato Scab. Vt. Agri. Expt. Sta. Bui. 184 : 3-64, Figs. 

1-6, pis. 1-12. 
Mann, Thos. F. 

1911. The Fusarium Blight Wilt and Dry Rot of the Potato. 
Ohio Agri. Expt. Sta. Bui. 229 : 229-336, pis. 1-15. 
McAlpine, D. 

1911. Handbook of Fungous Diseases of the Potato in Australia 
and Their Treatment, with 158 figures. Dept. of Agri- 
culture, Victoria. 
Melhus, I. E. 

1913. Silver Scurf — A Disease of the Potato. U. S. D. A., Bur. 

PI. Indus., Circ. 127: 15-24, Figs. 1-4. 
Melhus, I. E. 

1914. Powdery Scab (Spongospora subterranea) of Potatoes. 

U. S. D. A., Bul. 82 : 1-16, pis. 1-2. 



224 The Potato 

Mums. I.E. 
1915. Hibernation of Phytophthora [nfestans of the Irish Potato. 
I'. S.D. A., Jour, of Agri.. Research Bui. 5 : 71- L02, Figs. 

1-3, pis. I S. 

Melhus, I. E. 

L916. Germination and [nfestion with the Fungus of the Late 
Blight of Potato. Wisconsin Agri. Expt. Sta., Research 
Bui. 37: l 04. Figs. l-S. 

MORSE, W, J. 

L909. Black-leg A Bacterial Disease of the Irish Potato. 
Maine Agri. Expt. Sta. Bui. 174 : 309-328. 
Morse, W. J., and Shapovalot, M. 

1914. The Rhizoctonia Disease of the Potato. Maine Agri. 
Fxpt. Sta. Bid. 230: L93 216, Figs. 61-73. 
Morse, W. J. 
L914. Powdery Scab of Potatoes. Maine Agri. Fxpt. Sta. Bui. 
227:89-104, Figs, ll -50. 
Mi nn, M. T. 

1912. Lime Sulfur vs. Bordeaux Mixture as a Spray for Potatoes. 
Part 11. New York (Geneva) Agri. Fxpt. Sta. Bui. 

352:319 326. 
Orton, W. A. 

L913. Potato Tuber Disease, CJ. S. D. A., Fanners' Bui. 544: 

3-16, Figs, i L6. 
Orton. W. a. 

1914. Potato Wilt. Leaf Roll and Related Disease. F. S. D. A.. 
Bui. 64: L-48, pis. 1 1 1. 
Smith, F. F., and SWINGLE, IX B. 

L904. The Pry Rot of Potatoes due to Fusarium Ox\ sporum. 
F. S. D. A.. Pur. PI. Indus., Bid. 55:3 64, pis. l-S. 
Smith, F. F. 

lS9t>. A Bacterial Disease of the Tomato, Eggplant and Irish 
Potato. U. S. D. A.. Div. Veg. Phys. and Path., Bui. 
L2: 3 25 
Sn\ ENS, F. P.. and 11 u t , J. G. 
L913. Diseases of Economic Plants. (The Macmillan Co.)> 

New York. I 513, Figs. 1-214. 

Stew lrt, F. C, French, (5. T, and Sirrine, F. A. 

L912. Potato Spraying Experiments - L902-1911. New York 
(Geneva) Agri. Fxpt. Sta. Bui. 349 : 99-139. 



Control Measures 225 

Stewart, F. C, and Gloyer, W. O. 

1913. The Injurious Effect of Formaldehyde Gas on Potato 

Tubers. New York (Geneva) Agri. Expt. Sta. Bui. 369 : 
385-416, pis. 1-2. 
Stewart, F. C, and Sirrine, F. A. 

1915. The Spindling Sprout Disease of Potatoes. New York 

(Geneva) Agri. Expt. Sta, Bui. 399 : 133-143, pis. 1-3. 
Stewart, F. C. 

1916. Observations on Some Degenerate Strains of Potatoes. 

New York (Geneva) Agri. Exp. Sta. Bui. 422:319- 
357, Pis. 1-1 2. 
Stuart, Wm. 

1914. Disease Resistance of Potatoes. Vt. Agri. Expt. Sta. 

Bui. 179 : 147-173, Figs. 1-8. 



CHAPTER XII 
HARVESTING THE POTATO 

There are several important considerations bearing 
upon the harvesting of the potato crop. These must be 
kept in mind when one is planning the time and method 
of harvesting, if the best returns are to be realized. Im- 
proper attention to any of these points may result in a 
very material decrease in the crop. 

In the first place, the harvesting should be done at such 
a time and in such a manner as to give the maximum 
yield of tubers possible for that season. This means that 
we are to let the processes of starch formation and storage 
go on as long as they will. Secondly, we should aim to 
employ such methods as will give us potatoes of the best 
cooking and keeping qualities. And thirdly, we must 
eliminate, as far as possible, all traces of disease from the 
crop. Each operation in the process of harvesting should 
be carried on with careful consideration of its effect on 
total yield, quality and disease. 

Time to harvest 

The time of harvesting is influenced by the weather 
conditions and by the kind of potatoes grown. In general, 
one does not need to be as particular with early potatoes 
as with the late varieties. Early potatoes may be dug 
as soon as they are large enough to eat. Late potatoes, 

226 



Harvesti?ig the Potato 



227 



generally speaking, should be left in the ground as long 
as is possible without freezing. It should be remembered 
that starch is being formed and stored as long as the tops 
of the plants are green. To harvest the crop before the 
tops die, therefore, means a loss in quantity of potatoes. 
Early varieties may be dug a week or two before maturity, 
providing the higher price a bushel more than compen- 
sates for the decrease in yield. Late potatoes, which 
are usually stored for part or all of the winter, should 
preferably be fully mature and in good condition when 
harvested. 

Kohler, 1 of the Minnesota Experiment Station, presents 
some interesting data on the results of digging potatoes 
during the period of development. The variety on which 
the studies were made was the Early Ohio. The tubers 
were planted by hand on June 3, and the diggings were 
begun about two months later and continued at intervals 
of about a week, until the tops of the plants had died : 

Table XII. — Results from Digging Early Ohio Potatoes 
at Intervals during the Period of Development 

(In Bushels to the Acre) 





M 
& U x 


a a 

a a 


a 






j 






a 


Date op 
Digging 


* A a 


5 n 
3g 


< 





s 
g 


< 

2 
m 


a 


< 


* a 

a H 






& < 




« 






< 


H 


M .J 




O a «! 


&2 


> 


< 


3 


& 


s 

CO 


O 


a o 


July 31 


. 


10.9 








1.2 


9.7 


27.8 


38.7 





Aug. 7 


7.5 


62.3 





3.3 


30.5 


28.5 


25.4 


87.7 


1 


Aug. 14 


7.6 


115.4 





29.3 


59.5 


26.1 


26.1 


141.5 


8 


Aug. 23 


7.2 


182.1 


6.7 


42.9 


97.3 


35.2 


21.1 


203.2 


22 


Aug. 30 


6.4 


226.8 


6.7 


93.5 


92.8 


33.8 


27.0 


253.8 


99 



1 Minn. Bui. 118. 



228 The Potato 

The plants took practically three months to mature. 
Three weeks of this time were taken up in coming through 
the soil. About five more weeks were consumed by the 
crop in getting ready to produce tubers. Most of the 
potatoes are produced during the last month of growth. 
During this last month, there was a daily gain of about 
7 bushels of marketable tubers to the acre — up to the 
time the vines died. 

The potatoes were classified as to size on the following 
basis : 

Small — If ounces or less. 
Near small — 2 ounces to If ounces. 
Medium — 5 ounces to 2f ounces. 
Large — 9 ounces to 5 ounces. 
Very large — over 9 ounces. 

This table warrants the conclusion that potatoes should 
be harvested after the tops die, if we are to secure the 
highest yield. It also shows that there is a loss of yield 
if we harvest the crop before it is mature, and that this 
loss increases with the increase of time between the date 
of harvesting and the time of maturity. 

In the case of early potatoes, it is often possible to 
obtain prices high enough to overbalance the loss in yield 
and to make it profitable to dig them before they are 
mature. 

Table XIII has been arranged from figures given by 
Kohler, to show relative prices at which potatoes should 
sell if dug one and two weeks before maturity. 

Potatoes which are harvested before the tops die and 
before the tubers can be easily separated from the stems 
are usually immature. Such potatoes are not up to the 
American standard of quality for cooking, and are almost 



Harvesting the Potato 



229 



sure to disappoint the buyer. The immature tubers are 
also poorer in keeping qualities than those which have 
matured on the vines. 



Table XIII. — Early Digging for Market 



Price when 
Mature 


Prices Which Must Be Obtained if Potatoes Are Dug 


1 Week before Mature 


2 Weeks before Mature 


25 1 
35 f£ 

50^ 


30 i 
44 i 
63 i 


41 1 





For several reasons it is best to harvest potatoes in dry, 
cool weather. The tubers should be dug when the soil 
is fairly dry, in order that they may go into storage 
in a dry condition and as free from dirt as possible. The 
cool weather prevents their wilting unduly and makes 
it possible to get them into storage in good condition. 
If the soil is not too moist, potatoes are best left in the 
ground for a time after the tops have died, at least until 
there is danger of a freeze. Most authorities agree that 
no harm results from such a practice as long as the soil 
condition is as described. In some sections this may be 
almost necessary, especially where several weeks of warm 
weather are likely to follow the dying of the vines. It is 
difficult to store potatoes successfully if there are two 
or three weeks of warm weather immediately after they 
have been put into storage. In the North, cold weather 
usually follows the dying of the vines so closely that it is 
best to dig and store as soon as the tops die, and occasion- 
ally the digging must be done while the plants are still 
green in order to save the tubers from freezing. Where 



230 The Potato 

there is any disease in the crop, the practice of leaving the 
tubers in the ground for a time after they have matured 
has a distinct advantage. The infected tubers start to 
rot in the ground, and when they are dug they can easily 
be discarded. Otherwise they are stored with the sound 
potatoes and frequently cause a great deal of rotting. 

The progressive grower of potatoes will have on his 
farm a breeding plot on which he is attempting to isolate 
one or two superior strains of the variety which he is 
growing. He ought to be constantly on the watch for 
plants which show promise, and bring in the tubers pro- 
duced by these for a tuber-unit test. Some time during 
the growing season the farmer should go through his 
commercial field and stake any plants which show quali- 
ties of unusual vigor, disease-resistance, desirable habit 
and so on. The product of such plants should be dug 
by hand, bagged separately and records taken as to 
uniformity, size, weight and so on. A consideration of 
the data taken on each plant will show the grower whether 
or not he should keep the tubers for further growing and 
selection. 

Methods of digging 

The method employed in getting potatoes out of the 
soil will depend a great deal on the area planted, the 
type of soil and the cheapness of labor. Formerly, all 
potatoes were dug by hand with spades or forks. Later 
on, many growers used an ordinary plow to lift them. 
Then a special type of plow, the shovel plow, was em- 
ployed. Later came the various types of mechanical 
diggers. 

Small plantings of potatoes must always be dug by 
hand, because of the high cost of the digging machines. 



Harvesting the Potato 231 

It is often necessary, also, to dig early potatoes by hand. 
In the early varieties the skin is tender and easily in- 
jured by the digging machinery. The tubers also cling 
to the underground stems and frequently have to be 
pulled off. A man will dig from | to ^ acres a day, 
depending on the yield and type of soil. 

Digging by plows is not to be recommended unless it 
is a case of getting part of the crop or none. The plows 
cut and otherwise injure many of the tubers, and they 
cover nearly as many potatoes as they turn up. Growers 
usually agree that hand-digging secures enough more 
potatoes than plowing to make the extra labor well worth 
while. 

When the planting is relatively large, it pays the grower 
to buy a good digging machine. Such machines work 
quickly and are usually very satisfactory. In heavy 
soils and stony soils, and in cases in which the plantings 
are deep, there is a question as to their efficiency. 

The type of machine commonly used in this country 
has a steel nose which runs under the row and lifts potatoes 
and soil onto a grating of iron rods. The soil falls through 
the grating and the potatoes travel along the rods and 
are dropped at the back of the machine on top of the 
ground. From two to four horses are used on such a 
machine. A good machine will dig from 3 to 6 acres of 
potatoes a day, and will keep from 10 to 15 men busy 
picking them up. A second type of digger, less com- 
monly used, has a revolving frame with forks which dig 
into the ground at right angles to the row. Potatoes 
and soil are thrown against a screen and the soil passes 
through, leaving the potatoes in a row upon the ground. 

When a digging machine is used, it is sometimes neces- 
sary to remove the dead vines from the rows before 



232 The Potato 

digging. This can be done by running a spike-toothed 
harrow across the field lengthwise of the rows. It has 
the added advantage of leveling off the ground where 
the soil has been hilled up about the plants. 

Picking and sorting 

It is usually considered best to let the tubers dry on 
the ground for two to six hours before picking them up. 
This results in a drying and falling off of the excess dirt 
and also toughens the skin and lessens its liability to in- 
jury in handling. If the potatoes are left for too long a 
time in the strong sunlight, they turn green and their 
eating quality is injured. 

Potatoes are usually picked by hand into bushel baskets 
or crates (see Plate XIV). Formerly it was the practice 
to empty these containers into a wagon box and to cart 
the potatoes to the storage, where they were shoveled 
into boxes. This method of handling usually resulted in 
considerable injury to the potatoes and greatly impaired 
their keeping qualities. At present, potatoes are usually 
hauled from the field in two-bushel bags or in one-bushel 
crates. 

Alva Agee * recommends the use of one-bushel boxes 
for carting potatoes from the field. Such boxes, he says, 
should be made of basswood or some other light wood 
and should be of 26SS cubic inches capacity. These boxes 
are best made 12i inches deep, 13i inches wide and 16 
inches long. The sides and bottom should be f inch 
thick and the ends i inch thick. The length of two such 
boxes is about equal to the width of an ordinary wagon 
bed. With high side-boards on the wagon, these can be 

1 Penn. Dept. of Agr. Bui. 105. 



*^M 


J?- 






_;i»p^, • ; * J^ 


P--'-| 




^SH 1 




d ^ ' T^.-i • •>, '-.'"^ 


/■^w. 


, %^^s 


II *. * •';. , : 1 


"■M 




■ffr — , - ■ % x$l 




"-^3 


P*?OHI 1 M it! WPi> •'• 
.1 ;1l3MiiHM«aBg- 


A 


i 


w'-jsmI 


Pill 


1*? 




^p^ife -1 


K> Sf*'" V--: 




fl . 






w'\ s 


MVaBl 




i$S8 






1 ''.^^JB 

1 Ir'H 






- ? :• 


{ ff/^BfiSL-i;* V ■;' ^.i 



o 



Harvesting the Potato 



233 



piled up in tiers and about 60 boxes put on a load. Boxes 
of this description can be purchased for about 18 cents 
each. Slat crates of cheaper construction can be had for 
about 12 to 18 cents each. These boxes are quite dur- 
able and with proper care should last 10 or 12 years. 

There are now on the market machines which dig and 
bag potatoes in one operation. Machines of this sort 
undoubtedly save a great amount of labor, and in some 




Bumper 

Hoard 



Fig. 17. One type of potato sorter. 

cases will prove to be good investments. We should 
remember, however, that potatoes harvested in this 
manner have no chance to dry off and are therefore more 
likely to rot in storage than those which have stood for 
a few hours on the surface of the ground. 

Where the weather will permit, it is usually advisable 
to sort potatoes in the field. Various types of sorting 
machines are used for this purpose (see Fig. 17 and Plate 
XV) . One is simply a wooden frame on runners, having 
two inclined sieves of heavy wire. The largest potatoes 
roll down the top sieve into a sack at the end. The 
smaller potatoes fall through the upper sieve on to a finer 



234 The Potato 

one, and the larger of these potatoes roll down into a bag 
at the end of that sieve. The very small potatoes and 
pieces of dirt fall through the sorter on to the ground. 
A horse can be attached to this sorter, and it can be drawn 
around the field as the men pick. 

Other sorters of a more complicated type are often 
used in grading potatoes, but most of these are too cum- 
bersome to be hauled about for field sorting. 

Some potato-growers are heartily in favor of washing 
potatoes after bringing them from the field. This is 
done by the use of sprayers, and the potatoes are poured 
on to racks to dry. Those who advocate washing claim 
that it not only makes the tubers more marketable, but 
that it also reduces the loss by rotting in storage. Other 
growers insist that the labor of washing is not worth 
while, and still others say that it is injurious to the potatoes 
to wash them. Experimental evidence on these questions 
is lacking. 

Labor and cost of harvesting 

It is difficult to make an exact estimate of the cost of 
harvesting an acre of potatoes, because of the differences 
in the methods, the skill of the laborers, the type of soil 
and the size of the crop. Only approximate figures, there- 
fore, can be given.. 

If the digging is done by hand, i to i an acre can be 
dug by a man in a day. Fraser l estimates the cost of 
such digging at from two to six, or even eight, cents a 
bushel. 

A machine will dig from 3 to 6 acres a day. If we 
allow three dollars a day for the use of the team and 
two dollars a day for the driver, the cost of digging an 

1 S. Fraser. "The Potato." 



Harvesting the Potato 235 

acre by machinery will vary from 87 cents to $1.67. As 
this machine, digging between 3 and 6 acres a day, keeps 
from 10 to 15 men busy picking, it would appear that 
about 3 men are needed to pick up the potatoes on an 
acre. 

If the potatoes are sorted in the field, this item must be 
added in figuring the cost of harvesting. The quantity 
which can be sorted in one day will depend a great deal 
upon the type of sorter used. From 500 to 1000 bushels 
can be sorted by a machine in one day. 

It is almost impossible to make an accurate estimate 
of the cost of hauling from the field to the storage cellar. 
The size of the wagon used and the distance of hauling 
will vary greatly, and even an approximation of the cost 
of this operation would probably be valueless. 

The grower should always remember that the care 
which he exercises in harvesting his crop will mean an 
appreciable difference in its marketability. Cut and 
bruised tubers bring a lower price when sold directly 
from the field, and they are a complete loss when put into 
storage. Poor judgment as to time and method of har- 
vesting will have a detrimental effect upon yield and 
upon quality. The farmer who spends time and money 
to raise a good crop of potatoes should be equally careful 
in getting his crop to the market or into storage in the 
best possible condition. 

REFERENCES 
Agee, Alva. 

1904. Potato Production. Kansas Agr. Report. 
Agee, Alva. Penn. Dept. Agri. Bui. 105. 

Bennett, E. R. The Colorado Potato Industry. Colorado Bui. 
Fraser, Samuel. 

1905. The Potato. N. Y. (Orange Judd Co.), pp. 143-146. 



236 The Potato 

Grubb, E. H., and Guilford, W. S. 

1912. The Potato. N. Y. (Doubleday, Page & Co.), pp. 111-118. 

KOHLER, A. P. 

1909. Potato Experiments and Studies at University Farm. 
Minn. Bui. 118. 
Macoun, W. T. 

The Potato and its Culture. Central Expt. Farms, Bui. 49. 



CHAPTER XIII 
MARKETS, MARKETING AND STORAGE 

It is of interest to know the quantity of potatoes which 
are marketed every year in the United States, in order 
to appreciate the importance of the marketing problems. 
Such a figure, of course, can never be very accurately ob- 
tained, because of the lack of statistics of various sorts 
necessary in computing it. It is possible, however, to 
make a calculation which is approximately correct. This 
figure should be considered only as an approximation. 

The following table of averages may help to give an idea 
of the number of bushels of potatoes which are marketed 
every year in this country : 

Table XIV. — Averages for 1904-1913 

Annual production 326,199,200 bu. 

Quantity marketed in the fall — 50 per cent . 163,099,600 bu. 

Quantity stored — 50 per cent 163,099,600 bu. 

8 per cent less on stored potatoes .... 13,047,968 bu. 

Quantity used for starch 5,000,000 bu. 

Seed needed for next year 48,286,000 bu. 

Number of farms raising potatoes 3,008,474 

Potatoes consumed on farms 75,211,850 bu. 

Bushels to be marketed (home grown) . . . 183,653,382 bu. 

Annual imports of potatoes 2,688,148 bu. 

Annual exports of potatoes 1,410,831 bu. 

Excess of imports over exports 1,277,317 bu. 

In figuring the seed needed, 14 bushels of potatoes were 
allowed to the acre. The number of farms raising pota- 

237 



238 The Potato 

toes is an average of figures for 1899 and 1909. An 
average of five persons to a farm is considered fairly re- 
liable, and each person is assumed to eat about 5 bushels of 
potatoes a year. 1 From these figures we can estimate the 
number of bushels eaten on farms. We have then figures 
from which we can compute, rather roughly, the number of 
bushels to be handled annually on the potato markets of 
the United States. 

From the above table, we see that nearly one-seventh of 
the potato crop has to be saved for next year. About one- 
twenty-fourth of the whole crop, or one-twelfth of the 
quantity stored, is lost through shrinkage and rotting. 
Starch manufacture and home consumption of potatoes 
on the farm also take some of the crop. The quantity 
left, after subtracting all of these from the crop, repre- 
sents, in a rough way, the number of bushels of American- 
grown potatoes to be handled on the market. If we 
then balance the imports and exports, and add the excess 
of imports to this figure, we have the total number of 
bushels of potatoes handled in the American markets. 
This is approximately 184,930,000 bushels, or 30,822 cars. 2 

According to statistics published by the United States 
Department of Agriculture, about 50 per cent of the 
potato crop has been sold by January first. A relatively 
large proportion of this quantity is sold by farmers at 
the time of digging, or shortly afterward. The following 
table 3 gives figures for the total of 19 Northern states : — 



1 The average annual consumption per capita in the United States is 3.5 
bushels. The consumption is higher than this in the North and lower 
in the South, where sweet potatoes are eaten in place of Irish potatoes. 
Funk, in Farmers' Bui. 635, finds an average farm consumption (483 
farms) of 5.7 bushels. 

2 Car of 600 bushels. 

3 Monthly Crop Report, January 31, 1916, p. 8. 



Markets, Marketing and Storage 



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240 



The Potato 



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Markets, Marketing and Storage 241 

It will be seen that there is an average difference in price 
for a bushel on December 1st and March 1st of only 3 
cents. The question which then suggests itself is "Does 
it pay the farmer to store potatoes over winter?" 

When we compare the prices obtained for a bushel on 
December 1st and March 1st, it would seem that the 
farmer loses money by storing his potatoes. Surely the 
difference of 3 cents a bushel does not begin to cover the 
extra cost of storage nor the extra shrinkage and loss 
through rotting. Why not sell all the potatoes at digging 
time, or at least before January 1st? There are several 
very good reasons for this. 

In the first place, it would be very difficult for the dealers 
to handle the whole crop of potatoes in the fall. They 
lack the warehouse room and the help to take care of all 
the crop at one time. Dealers would be swamped with 
potatoes for a short time, and then have no more to handle 
for a long time. Secondly, there is a shortage of rail- 
road cars in the fall, and it would be impossible to ship the 
whole crop at one time. Then, too, the farmer is pressed 
for time in the fall and can use his teams to better advan- 
tage than in hauling potatoes. He can better afford to 
cart potatoes in the winter, when there is less to be done. 

Probably the principal reason for not selling the whole 
crop in the fall is the automatic lowering of prices which 
follows an attempt to market too many potatoes at that 
time. The dealers in potatoes will take only so many 
bushels in the fall, and any sold above this quantity are 
sold at a constantly decreasing figure. By storing part 
of his crop, the farmer equalizes the distributing of it on 
the market and gets a better net return than he would 
by selling all shortly after digging. 

If prices hold up in the fall, it will probably be better 



242 



The Potato 



for the farmer to market the larger part of his crop at once 
than for him to store it. Occasionally, however, the stor- 
age of potatoes becomes very profitable. 

In 1914, with a crop of over 400,000,000 bushels, the 
price of potatoes dropped during the winter. In 1915, 
when weather conditions were unfavorable, and the crop 
suffered badly in storage, prices went up rapidly during 
the winter. The winter of 1915-1916 was one in which 
stored potatoes of good quality brought a high price. The 
following table of estimated values a bushel, taken from 
the United States Government Monthly Crop Reports, 
shows the range in price a bushel during the seasons men- 
tioned : 

Table XVII 



Crop Reports of 



June 
August 
September 
October 
November 
January- 
March. . 
April 




Marketing the crop 

The methods of marketing the potato crop may be 
simple, or they may become complicated, requiring several 
handlings and the services of a number of persons. 

Probably the simplest method of marketing the crop is 
for the farmer to sell directly to the consumer, either haul- 



Markets, Marketing and Storage 243 

ing the potatoes by wagon or shipping them. This can 
only be done when the farmer lives fairly close to market 
and where he has good storage facilities, so that he can 
sell small quantities at a time. Such a method of market- 
ing is usually highly satisfactory, for it gives the pro- 
ducer the highest possible share of the profits and the 
consumer the lowest retail price. The farmer may also 
sell locally to retail grocers, thus eliminating the services 
of one to three or four middlemen. Obviously, only a 
very small proportion of the total crop can be marketed 
in these ways. Such methods of marketing necessitate 
much labor, and require good storage accommodations 
and an intimate knowledge of markets. 

Marketing through local dealers 

It is usually necessary for the farmer to sell his potatoes 
to a local dealer, who in turn stores some of them and sends 
the remainder to the commission men in the larger cities. 
These dealers are familiar with the requirements of the 
different markets and are usually able to sell the potatoes 
to a better advantage than can the farmer. 

The local dealers or buyers are to be found in nearly 
all towns where large quantities of potatoes are being 
brought in by the farmers. They usually sort and bag the 
potatoes and load them in cars for shipping. Occasionally 
a farmer or a small group of farmers will load and ship a 
car, but the bulk of the crop is handled by local buyers. 
These buyers, according to Taylor, may be of several sorts. 
They may be agents of large potato companies in the cities, 
or they many be independent buyers who combine other 
lines of business with that of potato-buying, or they may 
be agents of farmers' warehouses or cooperative associa- 



244 The Potato 

tions. The large potato companies usually have from one 
to several buyers in the more important potato-growing 
sections, to purchase from the farmers and ship the pota- 
toes, at their direction, to the best markets. These buyers 
handle potatoes at 4 to 8 cents a bushel. The agents of 
the farmers' warehouses, who are dealing in other prod- 
uce as well and have lower running expenses, are able to 
handle a bushel for about 3 cents. 

In many of the large cities there are companies which 
handle only potatoes. These companies get potatoes 
from the farmers through the local buyers, and then 
by means of telegraph and telephone ascertain the 
best markets and direct the shipment of the cars to 
them. They are handling great quantities of potatoes 
and can afford to spend large sums in order to get their 
goods to the best market. Companies of this sort 
often pay telephone charges of over one thousand 
dollars a month. 

Where farmers can be persuaded to cooperate and to 
place faith in the organization and in its agents, the co- 
operative method of selling potatoes has proved very satis- 
factory. Such organizations have agents in the small 
towns near which the members live. These agents receive 
potatoes from the farmers, and ship them at the direction 
of the manager of the company. These managers have to 
compete with the large potato companies, and are often 
at a disadvantage in getting information as to markets. 
Farmers' companies should either be in touch with large 
distributors or arrange with some company for "buying 
information." 

Local dealers usually find it necessary to sort and clean 
the potatoes brought to them, since growers seldom 
make a practice of sorting carefully. Potatoes are sorted, 



Markets, Marketing and Storage 245 

bagged or put in barrels for shipment. Occasionally a 
farmer will insist that his potatoes be sold without being 
sorted before shipment. These are sorted in the city 
and the culls are thrown out. The grower gets nothing 
for the culls and he must pay the expense of freight on 
them. 

Grading 

Potatoes are poorly graded, and for this reason the cost 
of marketing is higher than in the case of goods which are 
classified by grades. Potatoes of several varieties are usu- 
ally raised in the same section, and it is often hard to fill a 
car with only one variety. Experienced potato-shippers 
sort and grade carefully and get a higher price a bushel 
than is ordinarily paid. One produce exchange in Vir- 
ginia has so standardized its potatoes that wholesalers 
order by wire, without seeing the goods. Sorting and grad- 
ing on the farm, or at least before loading on the cars, not 
only makes it possible to secure a higher price for the pota- 
toes, but reduces the cost of marketing as well. The 
farmer ultimately pays the cost of grading, and often after 
he has paid the freight on as much as a ton of dirt and 
culls. 

Packages 

Early potatoes are usually shipped in three-bushel 
barrels, covered with canvas, or in bushel boxes. The 
barrels, with covers, cost about 20 cents apiece. Bushel 
boxes — 13 X 16 X 13 inches deep — cost about $30 
a hundred. Seed potatoes are frequently shipped in 
double-headed barrels of 165 pounds capacity. These 
cost about 30 cents each. 



246 The Potato 

Late potatoes are usually shipped in burlap sacks, 
holding two bushels. Sometimes flour barrels are used, 
and occasionally the potatoes are shipped in bulk in car- 
load lots. 

Shipping 

When potatoes are shipped in bulk, it is necessary to 
line the whole car with lumber. If the potatoes are 
bagged, it is not necessary to line the car, but a false floor 
must be put in. It costs the local dealer ordinarily a 
little over $30 to line a car. 

In the winter, it is necessary to heat the cars, and a man 
has to be sent along with the car to regulate the heat. 
Here again the larger dealer has the advantage, since he 
can ship several cars at once and reduce the cost of heating. 

Water transportation plays an important part in the 
shipment of early potatoes from the southern states to 
the larger cities of the North. 

Most of our potatoes are raised near the larger towns and 
cities, and the distances of shipment are relatively small. 
Chicago receives potatoes from Michigan, Illinois, and 
Wisconsin, a large part of her supply coming from the last 
state mentioned. New York and Philadelphia get pota- 
toes from New York state, New England, Long Island, 
New Jersey and the southern Atlantic states. Only a 
few states raise potatoes for interstate shipment. Taylor 
says that three-fourths of the potatoes grown are consumed 
in the states which raised them. Maine raises 25 per cent 
of the potatoes for interstate shipment, Michigan 24 per 
cent, Wisconsin 20 per cent, Minnesota 16 per cent and 
Colorado 8 per cent. 

After reaching the city in which they are to be marketed, 
the potatoes may take any one of several courses to the 



Markets, Marketing and Storage 247 

consumer. Very often they pass through the hands of a 
commission man, and frequently they go directly to the 
wholesaler. In the larger cities, a considerable part of 
the crop goes to the commission man, who, in turn, dis- 
tributes it among the jobbers or wholesalers. The com- 
mission man may employ a number of salesmen, or he may 
depend upon an expert potato broker to bring in orders 
from the wholesalers. Often goods are shipped around 
the commission men to the brokers, and thence to the 
wholesalers. 

The diagram (Fig. 18) may help to make clear the 
methods of marketing potatoes. Perhaps it will seem that 
there are too many middlemen concerned in the market- 
ing of this crop. In many cases there are. We must not 
lose sight of certain conditions of potato marketing, how- 
ever. The retailer sells in small quantities, and he has no 
room to store more than a small supply of potatoes. He 
must needs depend upon the wholesaler for his supply. 
The wholesaler in turn has to cater to a fairly definite de- 
mand from the retailer. He cannot take everything which 
is sent to him by the farmer, but must have access to the 
supplies of the commission man in order to get the desired 
variety and grade. So we have the potatoes coming to the 
large dealer or commission man, who sells in small lots to 
the wholesalers, and the wholesalers divide the product 
into still smaller parcels and sell to the retailer. The 
lack of proper grading, the bulkiness of the goods, and the 
demand for small quantities at a time, tend to make 
necessary the services of several classes of dealers in the 
process of marketing potatoes. 

There is no chance to gamble on potatoes, as on wheat 
and certain other crops, since there are no exchanges where 
the traders can come together. The potato market is 



248 



The Potato 



6 



LO 



Fig. 18. Diagram illustrating interrelationships of producer, middle- 
men and consumer of potatoes. 1 . Farmer. 2. Agent of farmers' ware- 
house or of cooperative company. 3. Independent local buyer. 4. Local 
buyer for large potato company. 5. Wholesaler. 6. Commission man. 
7. Broker. 8 and 9. Retailer. 10. Consumer. 



Markets, Marketing and Storage 249 

not very highly organized, and exact market information 
is very difficult to obtain. 

Early and late potatoes 

The earliest potatoes to reach the northern markets 
come from the Bermudas and Texas in January and 
February. Florida and other southern states add to the 
supply a little later, and about the first of June a large 
quantity begins to come in from Virginia and other south 
central states. 

Early potatoes from southern New Jersey enter the 
market about July twentieth and those from the northern 
part of the state and from Long Island about ten days to 
two weeks later. Early potatoes from New York and 
Maine are usually marketed between the first and fifteenth 
of September. The southern potatoes have little effect 
upon the price paid for northern-grown potatoes, providing 
they are out of the market by August. If southern pota- 
toes are late in reaching the northern markets, potatoes from 
New Jersey, Long Island and Pennsylvania are sold in com- 
petition with them and consequently bring a lower price. 

The main crop of late potatoes begins to come into the 
market early in October. From then on, the extent of 
the sales and the price for a bushel depend upon many 
factors. Chief among these is the supply of potatoes then 
upon the market. 

Markets 

The larger potato markets of the United States are New 
York, Chicago, Minneapolis, St. Louis, Cincinnati, Den- 
ver, San Francisco and Boston. Chicago handles annually 
about 24,000 cars, or over 60 cars a day. Each of these 



250 The Potato 

cities draws upon several states for its supply of potatoes. 
The eastern cities often get European potatoes in years of a 
poor crop, and occasionally these potatoes get as far west 
as Chicago. 

Range and prices 

There are few crops which fluctuate as much in value 
as the potato. In a single season the prices may show a 
range of as much as 70 or 80 cents a bushel. The highest 
prices are usually obtained in the late winter and early 
spring just as the early potatoes come on to the market. 
This value is not likely to fluctuate a great deal while 
early potatoes are abundant, but it drops off rather sud- 
denly as soon as the late crop comes in. Usually the price 
for a bushel remains fairly constant through the winter, 
though it may fluctuate a little either way. Later in the 
winter it is likely to rise somewhat or to drop off slightly. 
These fluctuations in price are due largely to a change in 
the relation of supply to demand. 

In 1899, the farm price was as low as 22 cents in Iowa 
and as high as $1.10 in Arizona, with an average price the 
country over of 36 cents. In 1915, the prices ranged from 
35 cents in South Dakota to $1.15 in Florida, with an aver- 
age of 61.6 cents. These wide fluctuations in price illus- 
trate the effect of supply and demand upon the value a 
bushel. The average farm price a bushel for the years 
1906-1910 was 60.4 cents. The highest average farm 
price on December first, since 1866, was 79.9 cents in 1911, 
and the lowest in the same period was 26.6 cents in 1895. 
In recent years, Arizona has had the highest value to the 
acre, averaging $127.68 for the 5 years from 1910-1914, 
The lowest value to the acre during the same period was 
.43 in Missouri. 



Markets, Marketing and Storage 



251 



The following table 1 gives the prices received for a 
bushel by the Burlington County Farmers' Exchange of 
New Jersey, for four years : 



Table XVIII. 



Seasonal Variation in Farm Price for a 
Bushel 



Period 


1911 


1912 


1913 


1914 


July 12 . . 


$1.25-$ 1.35 








July 15-20 


1.25- 1.30 


$.65-$.80 


$.60-$.80 




July 25-30 


1.05- 1.20 


.68- .83 


.65- .68 


$.60-$.80 


Aug. 1-10 


1.05- 1.25 


.62- .80 


.65- .73 


.53- .70 


Aug. 20-31 


.80- 1.00 


.55- .60 


.60- .68 


.50- .58 


Sept. 1-15 




.48- .50 


.60- .68 


.52- .55 


Sept. 15-21 






.75- .80 





A survey of the figures published by the United States 
Department of Agriculture shows that the price paid for a 
bushel on December 1st tends to vary immensely with the 
size of the crop : 

Table XIX 



Year 


Production 


Farm Price — in Cents 


(000 omitted) 


December 1st 


1904 


332,830 


45.3 


1905 


260,740 


61.7 


1906 


308,040 


51.1 


1907 


298,260 


61.8 


1908 


278,990 


70.6 


1909 


289,190 


54.1 


1910 


349,030 


55.7 


1911 


292,740 


79.9 


1912 


420,650 


50.5 


1913 


331,530 


68.7 


1914 


405,920 


48.9 



1 N. J. Extension Bui., Vol. 5, 1915. 



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1910 




















































































































































































1915 











































































d 



/ 



Fig. 19. Average yields of potatoes to the acre, a, 50 bushels ; b, 
60 bushels ; c, 70 bushels ; d, 80 bushels ; e, 90 bushels ; /, 100 bushels ; 
g, 110 bushels. 

252 



Markets, Marketing and Storage 253 

The graph in Figs. 19 and 20 illustrates this same rela- 
tion between production to the acre and value a bushel. 

If the consumer of potatoes examines a list of farm prices, 
as published by the United States Department of Agricul- 
ture, he is usually surprised to find that he is paying at 
least double what is paid the farmer for a bushel of potatoes. 

Under present conditions the cost of marketing potatoes 
is relatively high. It could be cut down appreciably if 
farmers would cooperate in marketing and would grade 
their stock carefully. Taylor publishes statements from 
a potato merchant to show the distribution of the cost of 
marketing a bushel. 

The local buyer pays, on the average, three cents a 
bushel for the labor of handling the potatoes. Bags cost 
about 5 cents, and . the dealer asks a profit of about 2 
cents a bushel. 

The freight charges vary a great deal with the distance 
of shipment. Taylor says that it costs about 8 to Si- 
cents a bushel to ship from Wisconsin to Chicago. To 
the freight must be added the cost of lining and firing the 
car, when the potatoes are shipped in the winter. This 
will cost about 2 cents a bushel. It costs the small 
shipper from $7 to $10 a car for heating, while the large 
dealer will send through a string of 5 to 20 cars for about 
$1.50 each. We must count on a certain loss in transit 
through frosting and rotting. Then, too, under present 
methods of grading and marketing there is almost always 
a loss of 20 to 40 bushels of culls to a car, and occasionally 
as high as 100 to 150 bushels. These potatoes are a total 
loss to the buyer, and the freight paid on them is also lost. 
As a result of this loss on culls, the price for a bushel rises 
somewhat. 

The larger distributor or commission man usually nets 



254 



The Potato 



1000 






























































































































1870 
































































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1905 












































































































































































































1910 
























































































































































































































































I9lp 











































Fig. 20. Average prices of potatoes by the bushel, o, 30 cents ; b, 
40 cents ; c, 50 cents ; d, 60 cents ; e, 70 cents ; /, 80 cents ; g, 90 cents. 



Markets, Marketing and Storage 255 

about 2 cents a bushel profit in addition to his expenses 
of li to 2 cents a bushel. 

The wholesale dealer incurs an expense of 5 to 7 cents a 
bushel in draying to his warehouse and later distributing 
to the retailer. He must also make a profit on each bushel 
handled. 

There is also the retailer, whose profit must necessarily 
be high. This last profit varies from 15 to 30 cents. 

A summary of all expenses incidental to marketing the 
crop shows a cost of 39 to 70 cents a bushel : 

Table XX 

Retailer 15-30 cents 

Wholesaler 5-10 cents 

Transportation 8-10 cents 

Larger distributor . ' 3-4 cents 

Burlap sacks and car linings 3-5 cents 

Local dealer 5-11 cents 

39-70 cents 

The cost of marketing varies greatly, depending on a 
number of factors. The distance to market affects freight 
charges very directly. The time of year when the potatoes 
are shipped has a bearing on loss in transit and cost of heat- 
ing the cars. Costs are markedly influenced also by the 
number of middlemen helping in the sale of the potatoes. 
Each one must make a profit. There is a lack of definite 
standards of quality in potatoes, and consequently at 
each exchange of goods there is keen bargaining to buy 
low and sell high. The retailers' cost of marketing de- 
pends largely upon the quantities purchased at one time 
by the consumer, and the cost of delivering and of main- 
tenance. 

It is obvious that a lowering of the cost of marketing will 
be profitable both to the producer and the consumer. The 



256 The Potato 

hntor will be able to buy potatoes for less a bushel, and the 
former will receive a larger share of the retail priee than 
before. The farmer should aim to etit down the expense 
o( growing and hauling to the loeal buyer. He can lower 
freight charges by sorting carefully and thereby not pay- 
ing freight on culls. By grading his stock and market- 
ing the best, he can raise the priee which he receives a 
bushel. Perhaps the most effective means of lowering the 
cost of marketing is for the farmers to organize coopera- 
tive selling companies. Such organizations have most 
of the advantages of the larger potato companies, in the 
way of decreased cost of hauling and better marketing 
information. In some eases the number of middlemen 
can be etit down. We must remember, however, that the 
potato is a bulky crop of a perishable nature and therefore 
must be carefully held in storage while awaiting shipment. 
This necessitates, for part of the crop at least, the serviees 
of the large distributor who can hold the goods safely 
until called for by the wholesalers. There must be re- 
tailers who can sell potatoes in small lots to the consumer. 
Perhaps one or even two of these steps might be dropped 
ottt occasionally, and the expense of handling several times 
be eliminated. 

There are many factors which determine the priee of 
potatoes. A careful study of these and skill in forecast- 
ing as accurately as possible the probable priee which 
potatoes will bring from the time they are stored until the 
last of them are sold late in the spring will determine 
whether it will pay to store them or not. 

The farm priee of potatoes at digging time is usually 
very low. Most growers do not have storage facilities 
and must put their product on the market in the fall. 
This inereases the supply and lowers the priee. 



Markets, Marketing and Storage 



_rw 



The principal factor which will determine the advisa- 
bility of storage is the probable winter and spring price ; 
others are the soundness of the tubers at digging time; 
relative ease of getting them on the market in the winter ; 
their use for table stock or seed purposes and so forth. 

Ordinarily a low-price season, resulting from overpro- 
duction, will be followed by a season of high prices. The 
grower should be carefully informed concerning the 
acreage of the whole county during the growing season and 
the reported condition of the crop from different sections. 
An extensive acreage and a favorable season results in 
low prices. 

The average consumption per capita in the United 
States is from ;U to 4 bushels. If the acreage and weather 
conditions over the whole country are likely to produce 
a crop of over 100 million bushels, low prices may be 
looked for. The population of the United States is ap- 
proximately 100 millions. At the rate of consumption of 
oh bushels for each person, the total consumption will be 
350 million bushels. 

The United States Department of Agriculture issues a 
crop reporter each month which gives the condition of the 
potato and other crops from all over the country. It is 
issued free to all and arrives about the 20th of each month. 

The amount of importation of potatoes into the United 
States is regulated by the price here and elsewhere, which is 
in turn largely determined by the quantity of production. 
The protective tariff on potatoes is 10 cents a bushel. 

The basis for storage must take into account American 
production and the probable price and the foreign pro- 
duction and price. When home prices reach a high level, 
foreign potatoes are sure to become a. price-determining 
factor. 



258 



The Potato 



It is obvious that all seed stock must be stored either 
by the grower, who may save his own seed, or by some large 
concern, who may store it for sale to growers in the spring 
(see Fig. 21). Seed stock should, perhaps, be stored more 
carefully than potatoes for eating purposes. Complete 
dormancy is necessary if the seed is to produce a good 
crop. If storage is not carried out properly, the tubers 




Fig. 21. Potato storage house. 

become shriveled and are likely to produce long, weak 
sprouts, which greatly weakens them. Many growers 
follow the practice of storing stock in bags and turning 
the bags every week in the spring to break off the sprouts 
and prevent rapid deterioration. This practice when fea- 
sible seems to be very successful. 



CHAPTER XIV 
USES OF THE POTATO 

The potato is one of the most important vegetable 
foods. Its rise in popularity since its introduction into 
Europe has been very rapid. At first the tubers were 
regarded as poisonous, and only a few of the more ven- 
turesome dared to eat them. When these men found the 
potato to be edible, the people of France and Germany 
began to plant it as a reserve food in case other crops 
failed. By 1770 it had become a common field crop in 
Europe. These potatoes, however, were usually small 
in size and of poor quality, and for this reason they were 
used principally as a food for animals. The possibilities 
of improving the crop were soon learned, and by 1840 it 
was being widely used as a substitute for the cereals and 
other starchy foods. In 1900 it was estimated that the 
potato furnishes about | of the total food consumed in 
the United States. 

Although it is primarily a food crop, the potato has a 
great variety of uses (see Plate XVI). For a long time it 
was the chief source of commercial starch, and although 
cornstarch is now preferred, the starch of the potato 
is still used in large quantities to make sizing for paper 
and textiles. Another important use for potatoes is in 
the manufacture of industrial alcohol. This industry is 
almost unknown in this country, but in Europe it has 

259 



260 



The Potato 



attained large proportions. Potato flour, glucose, sirup, 
mucilage and a number of tinctures are also made from 
potatoes. In Europe the small potatoes and culls are 
used to feed stock, and the slops from the manufacture 
of alcohol are carted away daily for this purpose. 



USE FOR HUMAN FOOD 

So accustomed have we become to the potato that it 
is difficult to imagine our tables without it. It furnishes 
us daily with an abundant supply of nutrients at a rela- 
tively low price. Primarily it is a starchy food, but it 
also contains some protein and a little mineral matter, 

and it adds bulk 
to the food eaten. 
It is said that the 
potato represents 
3.9 per cent of the 
total cost of food, 
and furnishes 5.3 

Fig. 22. Composition of the potato, a, fat; per cent of the heat 
ft, crude fiber and other carbohydrates exclusive pn l nr : p « n^Priprl hv 
of starch ; c, protein ; d, ash. calories needed Dy 

the body. As the 
potato is somewhat deficient in protein and fats, it cannot 
be used exclusively in the diet, but must be combined 
with lean meat, legumes, eggs or other protein-supplying 
foods, and with cream, butter or other fatty substances. 
Not only does the potato furnish considerable nutri- 
ment, but it supplies it in an easily digestible form. The 
starch in potatoes is much more readily digested than 
the starch of cereals or other starch-producing foods. In 
Germany a gruel made from the pulp of baked potatoes 
is used to feed infants and invalids. \ 




Uses of the Potato 261 

It is said that about 20 per cent of the tuber is waste. 
As this percentage is mostly skin and that part of the 
cortical layer removed with it, the percentage will vary 
with the size of the potato, the shape and the care used 
in feeding it. About 62 per cent of the whole tuber is 
water, and about 78 per cent of the edible portion is 
water. Carbohydrates form about 18 per cent of the 
peeled tuber. About 2 per cent is protein and 1 per cent 
ash. The fat content is rather low, being only 0.1 per 
cent (see Fig. 22). A large proportion of the protein 
and minerals is contained in the outer layers of the potato, 
and frequently much of this is lost in careless peeling. 

Quality when cooked 

The requirements for quality in a cooked potato vary, 
depending on the personal taste of the user and on the 
particular way in which the tubers are to be cooked. In 
America a mealy, white-centered potato is usually pre- 
ferred for boiling, steaming and baking. Europeans fre- 
quently prefer a less starchy potato, which means one 
with a higher percentage of protein. Such potatoes are 
richer in flavor and of better substance than the mealy 
ones. In some sections of Europe a mealy potato is in 
demand for boiling, and a waxy potato for frying and for 
salads. If Americans were to discriminate in favor of cer- 
tain textures of flesh for special purposes, varieties meet- 
ing the requirements would undoubtedly be developed. 

There are many factors influencing the quality of a 
potato when cooked and its value as a food. Undoubtedly 
the nature of the soil in which the tubers are formed has 
some effect upon these characters, but, so far, no definite 
relation has been worked out. It is also true that disease 



262 



The Potato 



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Uses of the Potato 263 

and seasonal conditions affect quality. In addition to 
these factors, there are chemical composition, degree of 
maturity, conditions of storage and methods of prepara- 
tion for the table, all having an important bearing on 
quality and food value. 

There are three textures of flesh in the cooked potato 
as determined by the chemical composition : soggy, 
waxy and mealy. The soggy potato is usually rather 
low in starch and relatively high in protein. In potatoes 
of this type, when the starch grains are heated they swell 
up, but there are not enough of them to burst the cell- 
walls in the tuber and give the starchy and mealy condi- 
tion so often desired. The tuber more easily absorbs 
water and becomes wet and soggy at the center. The 
protein also tends to coagulate and make the flesh heavier 
than it is in the mealy potato. 

In potatoes of a waxy texture, there is a greater propor- 
tion of starch to protein. The protein serves as a frame- 
work which prevents the starch from forming flaky masses 
and holds the potato together better. Such potatoes are 
desired for salads and for garnishing meat dishes. 

In the mealy potato, the cells are packed with starch 
grains. These expand with the heat of cooking and tear 
apart the cell-walls, making the center of the tuber a 
mass of flaky starch. If the starch content is too high, 
the tubers will fall to pieces in cooking. The optimum 
starch content is about 20 per cent of the peeled tuber. 

Potatoes are of the best quality when they have ma- 
tured fully and have been freshly dug from the soil. At 
this time the starch has been fully developed. Immature 
potatoes are usually high in protein, and they frequently 
contain acids and sugars which affect their flavor. The 
albuminoids which are frequently found in immature 



264 The Potato 

tubers gelatinize on cooking and make the flesh moist 
and soggy. Potatoes with a netted skin and crisp flesh 
are most likely to be mealy when cooked. 

No matter how carefully potatoes are stored, there are 
changes in composition taking place all the time, which 
affect the quality. The tuber, like an apple, is a living 
thing, and life processes are going on in it, though to be 
sure they are slow. As the winter proceeds, enzymes 
begin to work upon the starch and sugars and to break 
them down. Water and carbon dioxide are given off as 
a result. This causes a loss of starch and a shrinkage of 
the tuber. The sugars developed usually give the potato 
a sweeter taste than is found in the freshly dug tubers. 
Towards spring the potatoes begin to sprout, and of 
course at this time the chemical changes are rapid. There 
is a rapid loss of mealiness accompanying the sprouting. 

The method of cooking has some effect upon quality 
and food value, but it is usually because of a modification 
of the texture or the combination of fats and other sub- 
stances with the potato in the process of cooking. Boiled 
potatoes are most likely to lose in food value during cook- 
ing. This loss can be minimized, however, by cooking 
with the skins on. Baked potatoes lose very little, either 
in nutrients or in quality, when cooked. They are 
usually more mealy than potatoes which have been boiled 
or steamed. Mashed potatoes are usually seasoned with 
milk or cream and butter. This makes them higher in fat 
than when they are boiled or baked. Potatoes fried in 
fat are richest in food nutrients. The water is largely 
extracted and much fat is absorbed. Where possible, it 
is best to cook potatoes with their skins on. Experi- 
mental studies have shown that when potatoes are boiled 
in the skins, practically no starch is lost and only a 



Uses of the Potato 265 

small amount of the protein and ash or mineral matter. 
Potatoes which are peeled and soaked in water before 
cooking often lose as high as 7 per cent of their nutrients. 



USE FOR STARCH 

The principal article of manufacture from potatoes is 
starch. Until cornstarch supplanted it, potato starch 
was largely used in cooking. Now it is mainly employed 
for making sizing for paper and textiles, and for other 
technical purposes. Potato starch has also sometimes 
been used as an adulterant of fine flours and starches. 

The total annual production of starch from potatoes in 
the United States is about 15,500 tons, of which 6000 
tons are produced in the county of Aroostook, Maine. 
The soil of this county is unusually well adapted to potato 
growing. 

Unless the price of marketable potatoes is very low, 
only the small injured or refuse potatoes are sold to the 
starch factory. Whenever the price of good merchant- 
able potatoes is above 50 cents a barrel, the farmers find 
it more profitable to sell directly to the market. 

Process of starch manufacture 

The potatoes which are kept in a storehouse are carried, 
after weighing, to a revolving washer about 12 feet long 
and 18 to 24 inches in diameter. They are pushed to 
the comminutor through the washer by means of a per- 
forated spiral or by arms attached to a revolving axle. 
A stream of water flowing in the opposite direction to 
that of the motion of the potatoes secures the final wash- 
ing with clean water. By the time the potatoes have 



266 



The Potato 



reached the comminutor they are practically free from 
dirt. A diagram of this machine is shown in Fig. 23. 

The rasping machine consists of a cylinder about 30 
inches in diameter and 36 inches long. It is made of 




Machine for washing potatoes. 



wood and is covered with pieces of sheet iron punched 
full of holes about f of an inch in diameter. These holes 
have the rough edges outward. This rasping machine or 
comminutor is shown in Fia;s. 24, 25. 




Fig. 24. Rasping cylinder or comminutor. 

The rate of revolution of the cylinder is about 600 a 
minute. It revolves as near a brace of hardwood as pos- 
sible, and the potato, being stopped from passing by the 
brace, is reduced to a fine pulp by the rapidly revolving 
drum. 



Uses of the Potato 



26' 



From the rasper the pulp falls on to a starch separator, 
the bottom of which is of fine wire gauze having 30 meshes 
to the inch, the openings being -£$ of an inch in diameter. 
The separator is slightly inclined, so that the shaking 




Fig. 25. Rasping machine (cross section). 

process gradually moves the pulp toward the lower end. 
This separator is of the same width as the rasps, namely, 
about 36 inches, and is about 12 feet long. 

During the progress of the pulp along the separator. 



268 



The Potato 



jets of water are thrown upon it from pipes arranged 
above. This water detaches the starch granules from the 
pulp, and the granules, being small, are carried through 
the meshes of the gauze, while the pulp is left on the 
screen and ejected finally at the lower end. 

The starch which 
is carried through 
by the water falls 
in large tanks, vary- 
ing in size from 20 
to 40 feet in length 
and width and from 
6 to 8 feet in depth. 
The starch settles 
to the bottom very 
quickly and the red- 
dish-colored super- 
natant water can 
be drawn off. In a 
few hours the starch 
has all settled in a 
hard, compact mass 

Fig. 26. Starch washer (interior view) . , ■, , , . » 

at the bottom or 
the tank. The proportion of starch and water is such 
that 4 inches of starch is overlaid with about 6 feet of 
water. 

The crude starch obtained in this tank is then thrown 
into another tank of a similar size which is fitted with a 
revolving stirrer; water is added in large quantities at 
the same time and the starch is beaten into a cream and 
again allowed to settle. The interior view of such a tank 
can be seen in Fig. 26. This process washes the starch 
and removes the larger portion of impurities. 




Uses of the Potato 269 

In the second settling the pure starch is first to go to 
the bottom, and when the water is drawn off it is found to 
be covered with a thin layer of starch mixed with various 
forms of impurities. This layer is removed separately, 
and the pure starch underneath is ready for the drying 
tables. 

The layer of dirty starch removed as above indicated 
is given a second washing and if necessary a third, until 
the starch is thoroughly cleaned. 

The most modern way of drying is to have the starch 
stream out on shelves made up of slats through which 
the dried starch can fall to the shelf below. The drying 
kiln is heated by steam pipes running along the bottom 
underneath the shelves. The entrance for air is so 
arranged that it will come in over the pipes and thus 
become dried. 

The starch is first placed upon the upper floors on these 
wooden slats which have openings of about ^ inch. This 
is the coolest part of the kiln, so that the starch which is 
most moist is subjected to the least amount of heat. It 
is not safe to submit very wet starch to a high tempera- 
ture, for there would be danger of converting it into a 
paste and rendering it unfit for market. When the starch 
is partially dried, it is raked over the grated floor and the 
particles which are dry enough to be easily detached fall 
through and strike similar grates below. This raking 
process continues until the starch in a fine powder form 
reaches the lower floor in a state of dehydration suitable 
for barreling. The dried starch is finally raked into a 
trough running alongside of the lower floor of the kiln, 
and from there it is placed in the barrels. 

It requires about 12 hours to complete the drying 
when the most efficient kilns are used, so that the kilns 



270 The Potato 

are charged twice a day. The size of the kilns is, of 
course, proportionate to the capacity of the house. For 
a house using 1200 barrels of potatoes a day the kilns 
are about 40 feet long and 30 feet wide, and the drying 
shelves are about 15 feet in height. 

After the starch is thoroughly dried, it is placed in 
heaps in order that the moisture may be evenly dis- 
tributed throughout the mass. It is evident from the 
method of drying that some parts of the starch come from 
the kilns drier than others, as this banking or heaping of 
the starch is very essential in order to get uniformity of 
moisture. After the mass of starch has become uniform 
in its content of moisture, it is placed in barrels and is 
then ready for transportation. 

Uses of potato starch 

Starch and its by-products have many uses in the 
technical and industrial world. It possesses peculiar 
properties rendering it especially valuable for use in 
print works. The makers of prints are even willing to 
pay a considerable increase in price for potato starch 
over that which they would have to pay for starch from 
Indian corn. 

In the textile industries, it has come to be used exten- 
sively and in many ways. 

It is used in the manufacture of cotton, woolen, linen 
and silk goods for three distinct purposes : as a sizing 
for the warp yarn before it is woven ; for finishing goods 
after they have been woven; in the form of dextrin or 
roasted starch, as a thickener, or vehicle for applying 
colors to the fabric. 

In Europe, especially in England, large quantities of 



Uses of the Potato 271 

potato starch are used for the manufacture of dextrin or 
British gum, as it is called ; in which form it is used for 
various kinds of mucilage, as, for instance, that applied to 
postage and other stamps. The manufacture of dextrin 
of this kind is an important branch of the industries con- 
nected with starch. 

The pomace or residue which is left in the manufacture 
of starch from potatoes has been used to some extent as 
a food starch, and its use as a food will be discussed later 
under food for stock. 

USE FOR INDUSTRIAL ALCOHOL 

Next to starch, industrial alcohol is the most important 
product of potatoes. The potato is one source of such 
alcohol, and in Europe, especially in Germany, is the chief 
source. As yet this sort of production in connection 
with potato-growing has not gained a foothold in the 
United States. But a brief survey of the wide extent of 
the practice in Germany may throw some light upon its 
possibilities. 

In Germany, with the extension of the cultivation of 
the potato, which gives a larger starch yield to the acre 
than the cereals, the distillation of alcohol has become 
largely an agricultural industry. The use in Germany 
of potatoes for making alcohol has steadily increased 
from 1,915,800 pounds in 1855 to 4,706,820,000 pounds 
in 1905. The consumption of potatoes has increased, 
therefore, nearly 2500-fold during 50 years. In this 
connection it must be remembered that the starch con- 
tent of potatoes has also been increased. The best 
indication of the growth of the potato alcohol industry 
is from the output of the finished product. 



272 The Potato 

1855 32,757,700 gallons absolute alcohol 

1860 42,003,825 gallons absolute alcohol 

1865 52,570,825 gallons absolute alcohol 

1906 . exceeded 115,444,445 gallons absolute alcohol 

Distillation is, therefore, a very important and exten- 
sive agricultural industry in Germany. There the potato 
is the principal source of alcohol, and the production of 
spirits from other substances is insignificant in comparison 
with that from potatoes. 

The agricultural significance of the development of the 
potato industry as worked out in Germany is manifold. 

1 . All the ingredients taken from the soil by the potato 
are returned to the soil. 

2. The mash, which is the product obtained after the 
starch has been converted into alcohol and the latter has 
been removed by distillation, is a valuable feed for cattle. 
This enables the farmer to maintain a large number of 
cattle, and they in turn provide the manure so necessary 
for the light soil. 

3. The introduction of a cultivated crop into the rota- 
tion has been of the greatest benefit, because it has made 
possible larger yields of grain. 

4. It has enabled the farmer to convert the unstable 
crop, especially of those varieties of poor keeping quali- 
ties, into a stable product, alcohol, which may be held as 
surplus stock for several years. 

As was shown above, potatoes have been used in other 
countries as a source of cheap alcohol, and the possibili- 
ties of its becoming a profitable enterprise in America are 
very promising; for conditions in this country indicate 
that large quantities of potato culls with the necessary 
starch content are available for this purpose at a price 



Uses of the Potato 273 

which would permit of the profitable manufacture of 
alcohol therefrom. Experimental work at the United 
States distillery has shown that the potato can be eco- 
nomically handled in manufacturing alcohol, and the 
farmer can convert frosted or inferior grades of potatoes 
into a source of revenue. It also furnishes in the resi- 
due, or slop, a feed for stock. In recent years, many 
persons have become so much interested in this industry 
that it seems advisable to give a somewhat thorough 
discussion of the methods of manufacturing alcohol from 
potatoes. 

The alcohol from potatoes is a result of the action of 
malt or acids on the starch, which is turned into sugar 
and then fermented to give this final product. The so- 
called "denatured alcohol" is prepared by the addition 
of such ingredients as will make the alcohol unfit for 
drinking purposes. This alcohol is used extensively in 
the manufacture of varnish, explosives, chemicals and 
many other commercial substances. It may also be used 
in various household appliances, both for lighting and 
heating purposes, and with much more safety than either 
kerosene or gasoline. 

This discussion is limited to the methods which can be 
used upon a farm, or by a farm community, in a small 
distillery handled by the farmer himself. The potatoes 
should of course have enough starch to be worth using 
for this purpose. From experiments it has been deter- 
mined that there should not be less than 6 per cent of 
sugar or starch before the materials can be considered 
suitable for the profitable manufacture of alcohol. 



274 The Potato 

The manufacture of alcohol from potatoes 

The first essential in manufacturing alcohol from potatoes is that 
the distillery should be centrally located in a potato-raising country ; 
and secondly, the railroad facilities should be such that delivery of raw 
materials and feed, and the marketing of the finished product, can 
be done at a minimum expense. An abundant supply of cold soft 
water is of almost equal importance. It is desirable that the plant 
be near a creek or stream from which water may be obtained and into 
which it may be drained after serving its purpose in the distillery. 

As the distillery cannot be run throughout the entire year, the 
machinery should be simple, practical and economical. Advantage 
should be taken of the laws of gravity to save pumping whenever 
possible. This can be done by arranging the apparatus so that each 
operation will be on a lower level than the preceding one; thus 
by elevating the raw material to a height suitable for the first opera- 
tion, it will flow from one apparatus to another by its own weight. 
All machinery requiring steam should be placed close to the boiler 
so as to avoid condensation caused by long pipe connections. Ex- 
haust steam from the engines and pumps should be used in the dis- 
tillery apparatus and the hot water from the condenser should be 
utilized as feed water for the boiler. Each piece of apparatus should 
have a capacity equal to the exact amount of work it is expected to 
do, the only exception to this being the boiler, upon the efficiency of 
which depends the proper working of each piece of apparatus. The 
boiler should be of a slightly larger capacity than is actually required. 

This following data on the cost of a distillery are of a supposed 
plant which has a capacity for handling 8000 pounds of potatoes 
in one working day of 10 hours. The building is one story high, 
with a ground space of 1000 square feet. The walls are constructed 
of any available material. In many cases farm buildings, such as 
barns and the like, could be used. Such a building will not cost 
more than $1500. Total cost of machinery and equipment not 
inclusive of motor power is about $9000. One 75-horsepower 
boiler and a 25-horsepower engine will be required and will cost about 
$1500. This would make a total investment of about $12,000. 

A day's expenses will include the cost of potatoes, barley, fuel 
and labor. Cull potatoes can be delivered at a distillery in some 
potato-growing districts at 25 cents for 100 pounds. At this rate 
the raw material for a day's run of 8000 pounds will cost $20. To 



Uses of the Potato 275 

convert the starch of the potatoes into sugar, there will be needed 
the green malt yielded by 120 pounds of barley, which at 70 cents a 
bushel will cost $1.75. 

The cost of fuel varies with the fireman, but with proper care and 
efficient use one ton at $4 should be enough for a day's operation. 
Three men will be required, consisting of a fireman and two laborers. 
This will total up to about $33 for daily operating expenses. 

Operating a distillery. — ■ The first process is to wash and then 
cool the potatoes so that the starch present can be thoroughly 
converted into sugar by the action of the malt. The potatoes are 
placed in a vacuum cooker and steamed until they are thoroughly 
cooked. The steam pressure in the cooker is allowed to rise to 50 or 
60 pounds. The entire time required for warming the potatoes and 
reaching the maximum pressure should be about one hour. The 
potatoes are stirred and the pressure held for about ten more minutes 
to insure a good cooking of the starch. Then the temperature of 
the cooked potatoes is allowed to fall to 212° F. The temperature 
of the cooked potatoes is further reduced by means of the vacuum 
pump to 140-145 F.° at which point the malt necessary to change 
the starch to sugar is added. About 2 pounds of malt is added for 
each 100 pounds of potatoes mashed. The green malt is crushed 
between rolls, while dried malt is ground in a mill before using. 
About fifteen minutes before the mash in the cooker is ready for 
malting, the malt already ground is mixed with water at the rate of 
1 gallon of water to 2.5 pounds of dried malt, or f gallon of water to 
same amount of green malt. This is prepared in a tub above the cooker 
and is dropped into the cooker when the temperature is down to 140° 
to 145° F. The diastase in the malt will dissolve the cooked starch 
and convert it into a fermentable sugar in about fifteen or twenty 
minutes, during which time the mash should be constantly stirred. 
This is kept up until the test for complete conversion shows no starch. 
This test consists in filtering a little of the mash into a white porce- 
lain dish and adding a few drops of iodine solution (2.5 drams potas- 
sium iodide and 75 grains iodine to 1 quart water and shake). If 
the mixture is blue, it shows the presence of starch, and it is then 
necessary to add more malt, or allow more time for conversion. The 
cleaned mash is pumped through the mash cooler, where it is re- 
duced to the " pitching " (this means temperature in which yeast 
can ferment) temperature, by circulating a constant stream of cold 
water around the pipes through which the mash goes. This tempera- 



276 The Potato 

ture most favorable to fermentation is between 60° and 70° F., depend- 
ing on the weather conditions and volume of the mash. At the same 
time the mash is run through the fermenter the yeast mash (about 
3 per cent by volume of the main mash) is also added. It is prepared 
in a tube above the fermenter and can be dropped into it. 

Fermenting the mash. — After the yeast and mash are in the fer- 
menter, the process of fermentation will begin and the sugar in solu- 
tion will be broken down into alcohol and carbon dioxide gas. The 
gas goes out into the air, and the alcohol remains. At this point, 
it is important to know the gravity and acidity of the "set mash" — 
as it is now called. The specific gravity indicates the amount of 
sugar and is ascertained as follows : Stir mash and filter small por- 
tion through cheesecloth into a cylinder. A Balling saccharimeter is 
placed in the filtered liquid. The reading at the level of the liquid 
should be 16° to 18°, showing that the mash contains 16 to 18 per 
cent of solids, most of which is sugar. The acidity of the set mash is 
determined by neutralizing a small portion of the mash in a normal 
solution of sodium hydroxide, and the amount of the latter required 
will represent the acidity of the mash. It is done in the following 
way : 20 cubic centimeters of the filtered liquid is placed in a beaker 
and the sodium hydroxide is slowly dropped in from a burette until 
the filtered liquid has been neutralized and will not turn blue litmus 
red or red litmus blue. The number of cubic centimeters of sodium 
hydroxide used will represent the acidity of the mash. After the mash 
has been set for ten or twelve hours, the fermentation will become 
vigorous and the temperature will rise. It should not be allowed 
to go above 80° F. or much of the alcohol will evaporate. To keep 
the mash cool, a coil with cold water passing through it is slowly 
raised and lowered through the mash. The fermentation is allowed 
to continue at a temperature of 60° to 80° F. for 72 hours. The 
gravity should fall and the acidity remain about the same during the 
process. The tests should be made every 24 hours. If the acidity 
rises too much, the fermenters are scrubbed clean with a 5 per cent 
solution of formalin or other disinfectant. This will clean out the 
butyric acid which often is the cause for raised acidity. 

Distilling the alcohol. — In Fig. 27 is shown a distilling apparatus 
adapted for the economic separation of alcohol from the mash. It 
is not complicated, as one would think at a first glance, but is very 
simple. The fermented mash is slowly pumped into a distilling ap- 
paratus, where it is brought into contact with live steam, which boils 



Uses of the Potato 



277 




Fig. 27. — Distilling apparatus for making alcohol from potatoes. 



278 The Potato 

it and carries away the alcohol in vapor form, which in turn is passed 
through a condenser, where it is reduced to a liquid. The distilling 
apparatus consists of two copper columns, A and B, A being to dis- 
til the alcohol from the mash and B where it is redistilled and raised 
to desired strength. The fermented mash is continually discharged 
from pump 1 and pipe 2 into mash heater 3. This heater is made 
up of a series of tubes through which the mash gas goes and around 
which the vapors from the boiling mash are passed when going from 
A to B. The heated mash leaves 3 through pipe 4 and comes in con- 
tact with steam. The mash goes through a series of chambers, where 
it is boiled and the alcohol relieved from it. This mash takes a down- 
ward course from one chamber to another, and its course may be 
followed by the shaded portions in A. By the time it reaches the bot- 
tom, the mash will lose all its alcohol, and this mash will be automati- 
cally discharged through 5. A small portion of the vapors will be 
sent through pipe 6 to the condenser 7, and be tested to see whether 
any alcohol is being lost in the "slop," as the discharged mash is 
called. The steam necessary to boil the mash comes into the 
bottom chamber through 8, and it boils the mash in this chamber and 
passes upward, boiling the descending mash in the various chambers 
and carrying with it the vapors. The plates within column A are 
so perforated as to allow the ascent of the vapors through it, but 
do not allow the mash to fall through it, because of the steam pres- 
sure. The vapors rise up through A and go through pipe 9 to the 
heater 3, where they are circulated around the tubes and then carried 
through pipe 10 over to B. The vapors coming from A contain a 
considerable amount of moisture and other impurities which are 
freed in B, which contains a series of chambers upon each of which is 
carried about 3 inches of liquid. The plates are not perforated in this 
column, but the vapors ascend through a central pipe and are de- 
flected downward by a hood over the pipe in each chamber and are 
forced to boil their way through the liquid in each plate. The 
arrows show their courses. These vapors become purer as they 
ascend until they reach the top chamber, from which they are de- 
livered to pipe 11 and thus into a cooler 12, where they are partially 
cooled. From the cooler they pass into pipe 13 and through it to 
the condenser 14, where they are reduced to a liquid. This cooling 
and reducing is done by circulating cold water around the tubes con- 
taining the vapors. The condensed vapor or alcohol is drawn off at 
the bottom of the condenser and allowed to flow through the test box 



Uses of the Potato 279 

15, where it can be examined for its purity and strength. The 
steam pressure in the apparatus is registered by the pressure gauge 

16. The alcohol afterwards passes through the test box into the 
storage tank 17 to be denatured. 

Wood alcohol and benzin are generally used as denaturing agents, 
though other ingredients may be used. The ingredients used must 
be authorized by the Bureau of Internal Revenue. 

Preparation of green barley malt. — There are two operations — 
the first being to steep or soak the grain, and the second, sprouting 
or growing it. The steeping consists of soaking the grain in water 
until it has absorbed sufficient moisture to enable it to sprout when 
spread upon the malting floor. Good barley malt can be obtained 
from a good grade -of barley properly steeped (for two or three days) 
and grown for a long interval of time (12 to 20 days) with a fair 
amount of moisture at a temperature not to exceed 60°-63° F. The 
malt should be thoroughly crushed before using. 

Control of operation. — It is advisable to operate a distillery only 
during the colder months, for instance from early autumn until late 
spring. During this time the temperature of the cooling water will 
be considerably lower, and the amount of water required correspond- 
ingly less, and the time required for cooling decidedly shortened. 
This means a shorter working day and consequently less wear on the 
machinery and a considerable saving of fuel. It is essential that a 
distillery be operated daily and not intermittently, as each day's work 
depends in a greater or less degree both upon that of the preceding 
and the following day. Another very important point is cleanliness, 
and upon this depends the final yield of alcohol in a great measure. 
Many injurious organisms will breed and work into the mash and 
hinder the process of fermentation. This may be remedied by run- 
ning water through the apparatus at the end of the day's work, and the 
walls of the building should be kept from mold by whitewashing. 

Preparation of a potato-yeast mash. — The yeast mash is prepared 
in a wooden tub equipped with a rake for stirring and with proper 
piping for heating and cooling. The volume of the yeast should be 
from 2 to 3 per cent of the main mash to be fermented and increased to 
ten times that of the yeast mash used to start it. Rye is best used 
to start with, and later the potatoes may be substituted. The rye 
and malt are mashed together. The malt should be left to work for 
about three hours, by which time the formation of the sugar will be 
complete. The gravity should be 20°-24° Balling. Then the mash 



280 



The Potato 



is soured by the addition of some acids (lactic acid is best) which will 
suppress organisms which infect starchy materials. It will take be- 
tween 24 and 48 hours to reach the right acidity, which is 2.5 or 3 cubic 
centimeters. Then heat and then cool. When temperature is about 
90° F., add the yeast (about 10 per cent of volume of mash). Then 
reduce the temperature to 60°-70° F. Allow to ferment for 24 hours, 
during which time the temperature will rise, but never allow it to get 
above 90° F. Then this can be used in needed quantities to be added 
to the main mash. 

USE AS STOCK FOOD 

The value of the potato as a food is great, for it is a 
very concentrated starchy food. When fed alone, it is in- 
capable of supplying all of the wants of the body. Ex- 
periments by Girarde showed that the feeding of too 
many potatoes to stock would decrease the digestibility 
of the protein, the fat and the crude fiber : 







Table 


XXII 










o 
o 

fa 


3 

s 
5 


m 
t 


CO 

P 

US 


2 « 

Kg 


g 

H 

Eh 
O 

« 


m 

< 
a 

Q 

H 

o 
n 


w 

m 

< 




< 


P 


£ 




fa 








Per 


Per 


Per 


Per 


Per 


Per 


Per 




Cent 


Cent 


Cent 


Cent 


Cent 


Cent 


Cent 


Potatoes . . . 


Pigs 


97.0 


84.5 




82 


91.8 


44.6 


Potatoes cooked . 


Pigs 


95.0 


82.0 




80 


97.6 


40.0 


Potatoes dried and 
















ground . . . 


Sheep 


80.1 




81.5 


19.5 


42.0 





(From S. Fraser. "The Potato.") 

It was also found to have increased the time of churn- 
ing butter from 36 to 86 minutes. There was no effect 
on the milk composition, but it did affect its behavior 
towards rennet, injuring the milk for cheese-making. 

Potatoes when fed to pigs have been shown to be al- 
most entirely digestible. 



Uses of the Potato 281 

Snyder found that potatoes, when fed with grains or 
some milled products like oil meal, beans or good wheat 
screenings, were very suitable for fattening purposes. 
In experiments with sheep and cattle a ration composed 
chiefly of potatoes afforded rapid gains in live weight, a 
large percentage in dressed weight of the slaughtered 
animals and flesh of excellent quality. 

Experiments in Minnesota have shown that potatoes 
are very digestible; when 100 pounds are fed to pigs, 
23.8 pounds dry matter are digested, while only 75 pounds 
are indigestible. At the Hohenheim and Proskern sta- 
tions, the results on this question showed that they may, 
for practical purposes, be assumed to be completely diges- 
tible. Snyder, at the Minnesota Station, found that 
though cooked potatoes were eaten in greater quantities, 
the digestibility was not increased. 

Thus, it can easily be seen that potatoes, especially 
when abundant and low in price, may be fed to all kinds 
of stock. In France, Girarde fed 55 to 66 pounds of 
cooked potatoes a day to fattening steers and 4^ to 6^ 
pounds to sheep. Von Fanche found uncooked potatoes 
good for all stock except pigs. He fed 60 pounds raw 
potatoes, 6 pounds oil meal and 9 pounds clover hay with 
salt to a 1000-pounds live weight a day to fattening steers. 
For milch cows, 25 pounds daily to a 1000-pounds live 
weight is the limit. For yearling ewes and wether sheep 
25 pounds to a 1000-pounds live weight a day is advised, 
and for fattening sheep 40 pounds. For horses about 
12 pounds to a 1000-pounds live weight may be given 
with other food. 

Stock should not be watered soon after feeding potatoes, 
but preferably about i hour before feeding. Potatoes 
are not valuable as a food for young animals as they are 



282 



The Potato 



deficient in protein and ash, hence should not be fed to 
growing cattle under two years old, lambs and young 
pigs, unless in small amounts. 

Alcohol slops or residue 

The residue remaining from the production of alcohol 
contains all the constituents of the materials employed, 
except that portion of the sugars and starch which was 
converted into alcohol during the fermenting period. 
This "slop" has been found, both in this country and 
abroad, to be a feeding stuff of high value, and should be 
fed to the stock which furnishes the fertilizer for the 
potatoes to be used in the distillery. 

Table XXIII 
Composition of the Slop 





Ash 


Protein 
N.X6.25 


Fat 


Sugar 


Starch 


Crude 
Fiber 


N. F. E. 


Potato . . . 
Potato skins . 
Slops . . . 


Per Cent 

4.39 

6.51 

11.26 


Per Cent 

10.06 
21.87 
30.00 


Per Cent 

0.29 
2.55 
0.69 


Per Cent 

1.59 
1.44 
2.29 


Per Cent 

70.35 

8.65 
2.98 


Per Cent 

2.26 

20.69 

6.54 


Per Cent 

10.55 

28.40 
46.24 



(From the U. S. D. A., Farmers' Bui. 410.) 



This table shows that the dry substance of the slops is 
a higher nitrogenous food than the potato. It is due to 
the fermentation of the starch and sugar resulting in a 
concentration of the nitrogenous material. 



Uses of the Potato 283 

Potato pomace 

Potato pomace is the residue which is left in the manu- 
facture of starch from potatoes. It contains nearly all 
of the fiber, protein, fat and a large part of the starch 
found in the fresh potato. As it comes from the factory- 
it has incorporated in it a large amount of water. 

In this country this pulp mass goes to waste, but in 
Europe the potato and beet residue are rather extensively 
used as feeds in the wet condition, 80 pounds to 125 
pounds being fed to cattle daily a head. There, however, 
the factories are running throughout the year, and the 
residue can be fed in the wet state. But here this is not 
possible, and as the wet residue cannot keep, some method 
must be devised to dry it out, for in the dry state it will 
keep well. 

Poultry food 

T. W. Saunders, in his book on the potato, very highly 
recommends the use of potatoes as a poultry food. When 
given in correct proportion, it will do good in a food. The 
starchy part of the potato is mainly used in maintaining 
the heat of the body. It is cheap and easy to prepare 
and generally liked by all classes of poultry. To get the 
right proportions, of course, one must take into considera- 
tion the condition of the birds, weather, temperature, 
method of housing, extent of liberty allowed and whether 
the birds are expected to produce eggs or to lay on fat 
and flesh. 

A cheap good diet used for layers that are at liberty is 
equal parts by weight of potato and bran. The potato 
should be boiled, and the latter mashed into the potato 
while hot and the mixture given warm. If the weather 



284 The Potato 

is cold, add some linseed oil or fat. For confined layers, 
the proportion of potato should be reduced. Malt culms 
or sprouts are very good in combination with potatoes. 

Indian meal, barley meal and rice meal should not be 
fed in combination with potatoes, for they lack nitrogen 
matter. 

For fattening poultry, large amounts of potato can be 
used. Ducks, geese and turkeys fatten well on a mixture 
of potato and midds. 

Dried dessicated potatoes 

In Germany the manufacture of potato cakes is estab- 
lished, and these can be used as a food. The cakes, of 
course, are much smaller in bulk than the fresh potatoes, 
but after the soaking in water before using, their original 
character is regained. While the flavor and appearance 
cannot equal those of good fresh potatoes, they are con- 
sidered appetizing and acceptable where fresh ones are 
unobtainable. In this form they can be easily preserved 
in the tropics and in the arctic region and thus furnish 
an excellent article of diet in a convenient form for trans- 
portation. 

Potato flour 

In Germany the manufacture of potato flour is very 
much advanced. Rye flour is improved for baking by 
its addition. During the winter of 1914-1915, when 
there was a shortage of flour, owing to the European 
war, potato flour was used to make cakes and bread. 
Cakemakers and confectioners used it mixed with wheat 
flour. 



Uses of the Potato 285 



REFERENCES 

Canon, Helen. 

1915. Potatoes in the Dietary. Cornell Reading Course Bui., 
Food Series No. 15. 
Gilman, J. W. 

1905. Quality in Potatoes. Cornell Bui. 230, pp. 503-525. 

GlRARDE, A. 

Potatoes as a Food for Cattle and Sheep. Journ. Agr. 
Proc. 59 (1895), No. 20, pp. 709-712. 
Grubb, E. H. 

1912. The Potato. N. Y. (Doubleday), p. 545. 
Henslow, G. 

1910. Origin and Best of Our Garden Vegetables and Their 

1911. Dietetic Values. Roy. Hort. Soc. Journ., 36, pp. 345- 
346. 

Lang worthy, C. F. 

Potato as a Food. U. S. D. A., Farmers' Bui. 295. 
Niviere and Humbert. 

1895. Manufacture of Potato Cake. Abs. in Journ. Bd. Agr., 2 

(1895), No. 2, pp. 190. 
Parow, E. Potato Drying in Germany. Mitt. Deut. Landw. 

Gesell., 21 (1906), No. 25, pp. 264-266. 
Searl, O., Springer, J., and Krus, M. J. Manufacture of Potato 

Starch. Tidsske-Norske Taudbr., 4 (1897), No. 5, pp. 

203-208. 
Skinner, A. P. 

1910. Manufacture of Potato Spirit in Germany. Daily 

Cons, and Trade Repts. (U. S.) 13, No. 148, 1167- 

1169. 
Smith, C. D. 

1896. Feeding Value of Potatoes. Mich. Sta. Rpt. 107. 
Snyder, H. The Composition and Digestibility and Food Value 

of Potatoes. Minn. Sta. Rpt. 8 (1895), 83-96. 
Wente, A. O. Potato Culls as a Source of Industrial Alcohol. 

U. S. D. A., Farmers' Bui. 
Wiley, H. W. The Manufacture of Starch from Potatoes and 

Cassard. U. S. D. A., Div. of Chem., Bui. 58, pp. 

48. 



286 The Potato 

Wiley, H. W. Potato as a Food. Compt. Rend. Acad. Sci., Paris 

(1897), No. 1, pp. 43, 46. 
Wiley, H. W. Potato as a Food for Milch Cows. Journ. Agr. 

Pract., 58 (1894), No. 28, pp. 46-47. 
Wiley, H. W. Potatoes as a Food for Beef Cattle and Sheep. 

Journ. Agr. Pract., 58 (1894), No. 28, pp. 43, 46. 



CHAPTER XV 
COST OF GROWING POTATOES 

The cost of growing potatoes is very variable, depend- 
ing upon many factors. The cost not only varies among 
different sections of the country, but among farmers in 
the same section. The price of land, use of machinery, 
amount of spraying and extensiveness of operations are 
only a few of the factors which determine the cost. When 
figures are compared from many areas, however, a con- 
siderable uniformity is found to exist. 

Costs are given in the following pages from widely 
separated areas. They will give the reader a fairly 
accurate idea of the average expense involved in growing 
an acre of potatoes in different regions. 

Place — Twin Falls County, Idaho. 

Authority — Grubb and Guilford, "The Potato." 

Detailed cost of producing a 150-bushel crop as fol- 
lows : — 

Plowing $3.00 

Harrowing .75 

Floating 1.00 

Seed, average planting 700 pounds at 2 cents 14.00 

Planting 2.50 

Irrigating first year 5.00 

Cultivating three times at 50 cents .... 1.50 

Digging . 1.50 

Picking — 150 bushels at 4 cents .... 6.00 

Sacks — 75 at 7 cents 5.25 

Hauling to pit 2.00 

Total $44.00 

287 



288 The Potato 

"If potatoes are worth 50 cents a bushel, this crop 
would sell for $75, leaving a profit of $30.50 per acre, 
not deducting rent or interest or taxes. 

"If, however, the grower produces a 600-bushel crop, 
the cost of producing (figuring twice as much seed and 
increased cost of the operations) would be about $95.75. 
The crop would sell (at 50 cents a bushel) for $300, leav- 
ing a profit of $204.25." 

Place — Colorado. 

Authority — Greeley Commercial Club. 

Plowing $2.50 

Leveling and harrowing 1.00 

Seed 5.00 

Planting 1.50 

Cultivating 2.50 

Irrigating 1.50 

Digging 7.50 

Sacks 7.50 

Marketing 6.00 

Total $35.00 

"This estimate is based on what is considered a good 
yield of from 200 to 300 bushels per acre. The first six 
items are practically uniform whatever the yield may be, 
while the last three depend upon the yield per acre, so 
that a poor yield or a failure reduces the cost per acre 
by about one-half and an extremely large yield increases 
it accordingly. 

" The price of Colorado potatoes has a wide range from 
year to year, but the average price for the past ten years 
has been 65 cents per hundred pounds." 

Place — Kansas. Forty representative growers from 
thirty-two different counties. 

Authority — Report of Kansas State Board of Agri- 
culture, 1904. 



Cost of Growing Potatoes 289 

Average cost of plowing ....... SI. 20 

Harrowing .54 

Seed 7.25 

Planting 1.35 

Cultivating 1.66 

Digging and marketing 8.85 

Wear and tear of tools and rental of land or 

interest on its value 4.42 

Total cost per acre, or 122 bushels . $25.27 

Averages of other items, gathered from those furnish- 
ing the forty foregoing reports, are as follows : 

Average number of years each of the forty reporters has 

raised potatoes in Kansas 18 

Average number of acres raised by each annually ... 26 

Average quantity of seed planted per acre (bushels) . . 9 

Average yield per acre (bushels) 122 

Average value of potato land per acre $60 

Statements of ten of the growers reporting who are 
most extensively producing potatoes for commercial 
purposes, in the Kaw Valley, average as here shown : 

Average cost of plowing $1.45 

Harrowing .51 

Seed 8.05 

Planting .65 

Cultivating 1.46 

Digging and marketing 11.00 

Wear and tear of tools and rental of land or 

interest on its value 6.85 

Total cost per acre, or 154 bushels . $29.97 

Average number of years each of these ten reporters has 

raised potatoes in Kansas 18.0 

Average number of acres raised by each annually . . 80.0 

Average quantity of seed planted per acre (bushels) . 10.4 

Average yield per acre (bushels) ......... 153.7 

Average value of potato land per acre $105.00 

u 



290 The Potato 

Place — Ohio. 

Authority — Terry, T. B., and Root, A. I., "Potato 
Culture." 
Yield per acre — 250 bushels. 
Average price — 40 cents. 
Profit per acre — $61.06. 
Detailed cost as below : — 

Plowing $2.00 

Harrowing with Thomas and three horses .33 

Rolling 25 

Eight bushels seed at 50 cents, average . 4.00 

Cutting to one eye 1.50 

Planting with planter 1.00 

Harrowing three times . .45 

Harrowing four times with weeder ... .80 

Cultivating eight times, once in a row . . 3.36 

Bugs 2.00 

Hand pulling or cutting weeds .... .75 

Digging with four horses 2.50 

Picking up and storing 3.00 

Marketing, three-mile haul 6.00 

Manure 5.00 

Interest on value of land $100, at 6 per cent 6.00 

$38.94 

Dodge says: "The more expensive method of growing 
potatoes usually gives a yield of 275 bushels or more to 
the acre. Unless an application of barnyard manure is 
made in addition to the expense estimated at an added 
cost of from $5 to $10 per acre, the less expensive method 
rarely produces more than 125 bushels per acre and in a 
great many instances decidedly less than 100 bushels per 
acre. The increase in yield as a result of the more costly 
method is sufficient to more than pay the difference in 
cost, supposing potatoes to sell as low as 33| cents a 
bushel. One hundred and twenty-five bushels per acre 
grown at a cost of $15 per acre and sold at 33^ cents a 



Cost of Growing Potatoes 



291 



bushel yield a net profit of $26.66 per acre. Two hun- 
dred and seventy-five bushels per acre grown at a cost of 
$60 per acre and sold at 33 1 cents per bushel yield a 
net profit of $31.66 per acre. The second profit is $5 
more per acre than the first. 

"A farmer in Van Buren County, Michigan, states 
that his potato crop, mostly marketed in the fall, sold at 
an average price of 44 cents a bushel for a period of ten 
years. At the latter price the more expensive method of 
culture would yield a profit of $61 per acre, against 
$40 from the cheaper method. Furthermore, some of 
the leading potato dealers of the North have stated em- 
phatically that a better quality of potatoes is normally 
obtained with large yields than with small." 

Place — Maine and Wisconsin. Dodge says the Wis- 
consin figures will represent the expense put into grow- 
ing the crop in most localities where potato growing is 
carried on, on a less expensive and thoroughgoing basis. 

Authority — Dodge, L. G., Farmers' Bui. 465. 



Cost of Supplies and Labor with 
Rent op Land 


Maine 


Wisconsin 


Harrowing ........ 

Seed 

Digging 

Total 


$1.50 

.50 

24.00 

5.00 

.75 

.75 

3.50 

3.00 

6.00 

15.00 

$60.00 


$1.25 
.25 

2.50 
.60 
.60 

1.90 
.80 * 

2.10 

5.00 
$15.00 



1 For beetles only. 



292 The Potato 

Place — Maine. 

Authority — Bulletin of the Maine Department of 
Agriculture, March, 1914. 

Average cost of one acre of potatoes from records of 
ten potato growers in different localities in the state : — 

Cost of plowing $2.85 

Harrowing four times 4.00 

Fertilizer 36.00 

Applying 2.00 

Seed, 13 bushels at 80 cents 10.40 

Cutting seed 1.75 

Planting 4.00 

Cultivating four times 4.00 

Hoeing three times 3.00 

Spraying five times at $1.15 5.75 

Harvest 14.00 

$87.75 

Place — Maine. 

Authority — Cleveland, E. L., Aroostook County, 
Maine. 

Commercial fertilizer 1500 to 2000 pounds . $28.50 to $35 

Preparing ground for seed 3.00 

Seed, 600 pounds 7.00 

Planting 2.50 

Cultivation 3.50 

Gathering or harvesting 7.50 

Preparing for market .50 

Wear and tear on implements .50 

Rent of land (tenant farmer pays) .... 10.00 to 20 

Bordeaux mixture 4.00 

Paris green .50 

Hauling to market 3.50 

Average yield of product per acre .... 220 bushels 

Average value of product per acre .... $88.00 

Average size of fields 15 acres 

Average value per acre of land growing such 

crops $75.00 to I 

Profit per acre 17.00 



Cost of Growing Potatoes 293 

"Much depends on the weather conditions as to the 
cost of applying bordeaux mixture, paris green, cost of 
cultivation, labor and general net results. 

"The above estimates may be regarded the average 
for a series of years." 

Place — Maine. 

Authority — Hurd, Prof. W. D., formerly dean of the 
College of Agriculture, University of Maine. 

From records for several years on the college farm at 
Orono, the cost of growing a ten-acre field of potatoes is 
about as follows : man and team labor are reckoned at 
$3.50 per day, extra men at $1.50 per day. 

Plowing at $2 per acre $20.00 

Harrowing five times, $3.50 per acre 17.50 

Fertilizer (home mixture) $30 a ton 225.00 

Seed, 130 bushels, 75 cents a bushel 97.50 

Disinfecting seed (labor and material) 3.00 

Cutting seed (by hand) at 6 cents per bushel . . . 7.80 

Planting, team and two men three days, $5 . . . . 15.00 

Harrowing or weeding before crop is up, four times . 10.50 

Cultivating crop eight times at $3.50 28.00 

Spraying six times ($1 per acre each application) . . 60.00 

Hand hoeing and pulling weeds once (if necessary) . 15.00 
Digging and hauling to storehouse or station at $15 

per acre 150.00 

Rent of land (5 per cent on $50 per acre value), 10 

acres 25.00 

Depreciation of implements (plows, harrows, planter, 

sprayer, digger, etc.), value $250 estimated at 10 per 

cent 25.00 

$699.30 



Value of crop, 225 bushels to acre (2250 bushels at 50 

cents) $125.00 

Value per acre 112.50 

Cost of growing per acre 69.93 

Net profit per acre 42.57 



294 



The Potato 



Place — New York. 

Authority — Results of a survey by the Department 
of Farm Management, New York State College of Agri- 
culture. 

Cost of Growing Potatoes 





1913 


1914 








18.0 




21.0 








185.4 




158.8 


Average acres per farm 






10.3 




7.6 


Average yield per acre 






102.7 




154.7 


Cost of Growing per Acre 


Amount 




Amount 




Seed 


10 bu. 
412 lb. 


$7.67 
5.17 


12.6 bu. 
431 lb. 


$8.03 








5.72 










6.14 


2.06 tons 


4.64 


Spray materials 








.83 




.80 


Man labor . . 






77.7 hr. 


13.30 


81.2 hr. 


15.57 


Horse labor . 






77.4 hr. 


10.66 


72.4 hr. 


12.41 


Equipment . . 








3.58 




3.71 


Use of land at 6 per cenl 




4.53 




5.18 


Use of buildings at 8 pei 














1.27 




1.09 


Interest at 5 per cent . 








.88 


All other costs . . . 




.63 




.04 


Total cost . . . 




$53.74 




$58.07 


Cost of marketing pei 














.12 




.05 


Cost of growing per bushe 


L 


.52 




.38 


Cost of growing and mar 










keting per bushel 




.63 




.43 


Profit per acre . . . 




7.38 




-16.03 


Profit per bushel . . 




.07 




- .10 


Profit per man, hour . 




.08 




- .18 



Cost of Groioing Potatoes 



295 



UIli 



Apr. May June July Aug. Sept. Oct. 



Apr. May June July Aug. Sept. Oot. 



Fig. 28. 



(see page 298) 



Fig. 29. 



Place — California. 

Authority — Shanklin, L. F., Lompoc, California. 
Quoted from Grubb and Guilford, "The Potato." 

L. F. Shanklin of Lompoc, California, estimates the 
cost of producing an acre of potatoes as follows : — 

Use of land (will rent for) $30.00 

Seed, 400 pounds at 1| cents 6.00 

Plowing and preparation 5.00 

Cultivation twice — hoeing once 1-00 

Digging and picking 3.00 

Sacks 5 cents, sacking 5 cents (100 sacks) 10.00 

Hauling 1-00 

$56.00 

His average crop is : — 

70 sacks first, 115 pounds to sack, at $1.30 per 100 . . $80.00 
30 sacks seconds, 120 pounds to sack, at $1.00 per 100 . . 36.00 
30 sacks cow feed or waste at 10 cents per 100 . . . 3.00 

$119.50 

Place — New York. 

Authority — Department of Farm Management, New 
York State College of Agriculture. 



Cost op Growing Potatoes 
in New York 


Steuben Co. 


Clinton & Franklin 
Cos. 


Yield per acre .... 
Acres per farm .... 


355.0 

131.0 

14.7 


300.0 
179.0 

7.2 



296 



The Potato 



Cost of Growing 



Seed 

Fertilizer .... 
Manure .... 
Spray materials 
Man labor . . . 
Horse labor . . . 
Use of equipment . 

Land 

Buildings .... 
All other costs . . 
Total cost of growing 

acre 

Total cost of growing 

bushel .... 
Cost of marketing per acre 
Cost of marketing per 

bushel 

Profit per acre . . . . 
Profit per bushel . . . 
Profit per man, hour . 



per 



per 



Amount 



10.2 bu. 
120.0 lbs. 
2.3 tons 



66.0 hrs. 
68.9 hrs. 



$9.48 

1.66 

4.61 

.20 

11.55 

10.33 

3.45 

3.00 

.81 

.45 

45.54 

.35 

5.80 

.054 
2.22 
.02 
.03 



Amount 



12 bu. 
407 lbs. 
3.4 tons 

110.4 hrs. 
88.6 hrs. 



$6.79 

5.77 

7.21 

.22 

17.65 

10.20 

3.94 

7.00 

1.56 

.12 

60.68 

.33 
6.32 

.044 
36.72 
.21 
.33 



Place — Utah. 

Authority — Harper, W. F., Smithfield, Utah. Quoted 
in Grubb and Guilford, "The Potato." 

Plowing, harrowing and leveling the land $5.00 

Fifteen loads of manure at 25 cents per load .... 3.75 

Hauling manure at 75 cents per load 11.25 

Seed 10.00 

Cutting and planting seed 9.00 

Cultivating, weeding and irrigating 5.00 

Picking and sacking 10.00 

Loading on car 4.50 

$59.00 

Results of a survey in New York state 

In the agricultural survey of Tompkins County, 
Warren, Livermore, and others : " The potato crop ranks 



Cost of Growing Potatoes 297 

third in value of crops, but the acreage per farm is very 
small, averaging 1.7 acres. Of 982 farms in four town- 
ships, only 33 grew more than 5 acres of potatoes and only 
2 grew over 10 acres. Nearly all of the crop is grown in 
this small way, but the crop is usually a profitable one. 

"Apparently the larger acreages are profitable. The 
average labor income of farmers growing more than 5 
acres of potatoes is $853. 

"Of 605 farms operated by owners, 11 sold over $500 
worth of potatoes. These men made good profits. The 
lowest labor income was $724, and the highest $2146 ; 
the average was $1511. The farms averaged 141 acres. 
An average of 6.3 acres of potatoes were grown per farm, 
with an average yield of 219 bushels per acre. The 
average receipts from the sale of potatoes were $732, 
which constituted 24 per cent of the total sales. 

"Of nine of these farms the most important sale was 
milk, with potatoes second. Each of the farms received 
some income from hay, grain, eggs, or lambs, etc. 
The average labor income on these farms was $1575. 

"One farm of 134 acres was a potato, hay and grain 
farm, with some sales of eggs, milk, etc. This farm gave 
a labor income of $1649. 

"One farm of 71 acres sold potatoes, lambs, hay, grain, 
eggs, etc., and 'made a labor income of $794. On many 
farms that have soils adapted to potatoes, it would seem 
desirable to increase the area of this crop. When the 
crop can be increased to ten acres per farm, it will justify 
the purchase of a planter, sprayer and digger. Only 
by growing a much larger acreage per farm can one afford 
this labor-saving machinery that will go far toward 
making the crop pay. It will also pay to try much 
heavier applications of fertilizer." 



298 The Potato 

Other survey results 

In a survey of the incomes of 178 New York farms, 
Burritt 1 obtained some interesting figures which show 
comparisons of certain kinds of farms. Unfortunately 
the number of potato farms in the survey was very small 
and may not mean very much, but the tables give a 
suggestive comparison. He says : " All farms were di- 
vided into two classes. Mixed or general farms are those 
on which no one source of income constitutes 40 per cent 
of the total income. Special farms are those deriving 
40 per cent or more of their income from one special 
crop or industry. This latter class was further divided 
into dairy, fruit, potato and truck farms." 

The seasonal distribution of man and horse labor is 
one of the factors which determine the feasibility of 
growing potatoes along with other crops, and represents 
no small measure of profitableness when considered in 
the whole farm scheme. The figures 28 and 29 (page 295) 
are used by Warren to represent the distribution of 
horse and man labor respectively, on 11 acres of potatoes. 
Black is work fixed as to time, white is plowing and 
marketing. 

1 Bui. 271, Agri. Expt. Sta., Cornell University. 



Cost of Growing Potatoes 



299 



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No. of farms . . . 
Average area 
Total capital . . . 
Real estate .... 
Machinery and tools 

Other live stock . . 
Seed and feed . . . 
Miscellaneous . . . 



302 



The Potato 



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304 



The Potato 



Place — New York (St. Lawrence County). 

Authority — Circular of Information of the New York 
State School of Agriculture at St. Lawrence University, 
April, 1911. 

The detailed cost of growing an acre of early potatoes 
for the years 1909 and 1910 was as follows : — 

Early Potatoes 



Cost per Acre 



1909 



1910 



Yield (large), 192.22 bushels at 62 cents 

Yield (small), 26.65 bushels at 20 cents 

Yield (large), 122.15 bushels at $.477 . 

Yield (small), 22^ bushels at 20 cents. 

Plowing 

Harrowing 

Planting 

Cultivating 

Hoeing 

Spraying 

Digging and delivering 

Fertilizer, 2000 pounds 

Fertilizer, 1899 pounds 

Seed, 18| bushels at $1.18 

Seed, 17| bushels at $ .40 

Paris green 

Total cost per acre 

Profit per acre 

Loss per acre 



$119.18 
5.33 



$95.29 
29.22 



58.27 
4.50 



4.00 


2.01 


4.39 


2.25 


4.42 


4.29 


1.93 


3.01 


1.81 


.87 


8.49 


9.39 


18.19 


14.61 


28.00 






25.72 


21.66 






6.90 


2.40 


2.92 



$71.97 
9.21 



"The soil upon which the main crop of late potatoes 
was grown is a sandy loam. The field had no clover 
sod, indeed, no sod of any sort except the quack-grass and 
weeds. A higher cost for chemicals was necessary to 
make good this deficiency. Three and one-third acres 
of the field contained quack-grass and foul seeds. This 



Cost of Growing Potatoes 305 

land was plowed twice in the spring with frequent culti- 
vation, which very nearly destroys every trace of quack- 
grass. The low cost of hand labor on the field warrants 
the statement that weed growth was practically de- 
stroyed by cultivation before the potatoes were planted, 
and by the weeder after they were planted. It is impor- 
tant that we impress upon the users of weeders and smooth- 
ing harrows the absolute necessity of beginning opera- 
tion at once after the potatoes or seeds have been planted. 
If the weeds become rooted, even though they may not 
show very much above ground, the light-fingered tools, 
which are only safe to use on the growing plants, will 
have very little effect upon them. Farmers are often 
disappointed in the effect of weeders, simply because the 
weeder has given the weed the same encouragement which 
it gives to the plant under cultivation. 

"The seed potatoes which were kept in an outdoor pit 
during the winter were taken from the pit April 18th, 
spread thinly on the barn floor and stirred occasionally to 
prevent long sprouts from growing. They were planted 
at varying dates from May 28th to June 10th. None 
of the sprouts were broken in handling or planting. The 
pieces were cut as nearly cubical as possible, and weighed 
about 2 oz. each. The number of eyes varied from 1 to 
5, the seed ends often containing 5 to 6 eyes. No effort 
was made to reduce the size of the seed piece from the 
seed end of the potato, in fact it is a fatal error to do so. 
Only one or two stalks will develop. The pieces were 
dropped 14^ inches by 36 inches." 

"The cost by items does not show marked difference 
for the two years, with the exception of digging and 
delivering. A part of this saving was due to a lighter 
yield and a part to more economical methods of handling." 



306 The Potato 

Four and One-third Acres Potatoes (1910) 



Yield, 958^ bushels (large) at 40 cents 
Yield, 53 bushels (small) at 20 cents . 

Plowing 

Harrowing 

Planting 

Cultivating 

Hoeing, hand labor 

Spraying, 1050 gallons per acre . . . 

Digging and delivering 

73| bushels seed at 40 cents 

8234 pounds fertilizer 

42 pounds paris green 

Profit, $75.87 



$15.33 
9.75 
18.63 
13.02 
3.81 
40.70 
63.32 
29.40 

111.57 
12.60 



$318.13 



$383.40 
10.60 



$394.00 



Potatoes 



Cost per Acre 



1909 



1910 



Yield (large), 289f bushels at 40 cents 
Yield (small), 27 bushels at 20 cents . 
Yield (large), 22U bushels at 40 cents 
Yield (small), 12.2 bushels at 20 cents 

Plowing 

Harrowing 

Planting 

Cultivating 

Hoeing (hand labor) 

Spraying, 1000 gallons 

Spraying, 1050+ gallons 

Digging and delivering 

Seed, 16 bushels at 73 cents .... 
Seed, 17 bushels at 40 cents .... 

Fertilizer, 1800 pounds 

Fertilizer, 1900 + pounds 

Paris green, 7 pounds 

Paris green, 9.6 + pounds 

Total cost per acre 

Profit per acre 



.15.92 
5.40 



4.18 
1.90 
4.30 
1.73 

.68 
8.49 

24.01 
11.68 

25.20 

2.10 



$84.27 
37.05 



$88.48 
2.44 



3.54 
2.25 
4.30 
3.00 



9.39 
14.61 

6.80 

25.75 

2.91 



$73.43 
17.49 



Cost of Growing Potatoes 307 

Place — Minnesota. 

Authority — Bulletin 48, Bureau of Statistics, by Hays 
and Parker. 

The cost of producing potatoes, under garden condi- 
tions, is given on pages 308 and 309. 

Cost of hauling 

Potatoes are a bulky crop and the cost of hauling is 
no inconsiderable item. Andrews x says : " In many ways 
they are hauled under conditions similar to those under 
which grain is hauled, and the average cost per 100 pounds 
for hauling potatoes from farms to shipping points is the 
same as for wheat and 2 cents more than for oats, corn 
or barley. 

"The averages for the United States are affected more 
by the figures for the north Atlantic and north central 
states than by the other states and the territories, since 
about three-fourths of the potato crop of the United 
States is produced east of the Rocky Mountains and 
north of the Potomac and Ohio rivers and southern 
boundaries of Missouri and Kansas. 

"The average cost of hauling from farms to shipping 
points in this region is 9 cents per 100 pounds, or 5.4 
cents per bushel. The lowest average cost is for three 
counties in Rhode Island, where an average of three trips 
per day is made to and from shipping points, and the 
highest average cost in the north Atlantic and north 
central states is in South Dakota, where the average 
time of round trip between farm and shipping point is 
longer than one working day." 

1 Andrews. Cost of Hauling Crops from Farms to Shipping Points. 
U. S. D. A., Bureau of Statistics, Bui. 49. 



308 



The Potato 



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309 



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310 



The Potato 



Table XXXI. — Average Cost of Hauling Potatoes from 
Farms to Shipping Points 









S a 

8 u « 
a 5 o 




Average 


State or Territory 


Miles 
to Ship- 
ping 
Point 


Days 

for 

Round 

Trip 


Pounds 
in One 
Load 


Cost 
per 
Load 


Cost 
per 100 
Pounds 


Maine 


9 


7.6 


0.7 


2393 


12.58 


$0.11 


New Hampshire 




5 


6.6 


.6 


2330 


2.21 


.09 


Vermont . . . 




7 


7.1 


.6 


2321 


1.93 


.08 


Massachusetts 






3 


10.6 


.6 


2300 


2.40 


.10 


Rhode Island 






3 


5.0 


.3 


1933 


.98 


.05 


Connecticut . 






2 


6.7 


.7 


2500 


2.80 


.11 


New York 






34 


7.1 


.7 


2896 


2.49 


.09 


New Jersey . 






9 


4.8 


.6 


2583 


2.08 


.08 


Pennsylvania 






22 


6.6 


.7 


2809 


2.61 


.09 


Delaware 


1 


10.6 


.7 


1500 


2.80 


.19 


Maryland . 






7 


5.7 


.5 


2536 


1.62 


.06 


Virginia 






22 


9.1 


.8 


1880 


2.30 


.12 


West Virginia 






17 


12.2 


1.2 


1965 


4.21 


.21 


North Carolina 






27 


11.4 


1.1 


1437 


2.92 


.20 


South Carolina 






3 


9.9 


.7 


1267 


2.01 


.16 


Georgia . . 






16 


11.0 


1.0 


1466 


2.52 


.17 


Florida . . 






9 


7.7 


.6 


1544 

2748 


2.05 
2.39 


.13 


Ohio 


22 


7.2 


.7 


.09 


Indiana . . 






12 


6.4 


.6 


3075 


1.72 


.06 


Illinois 






13 


6.0 


.6 


2700 


1.94 


.07 


Michigan . . 






47 


8.0 


.7 


2766 


2.25 


.08 


Wisconsin 






28 


9.5 


.8 


2595 


2.46 


.09 


Minnesota 






20 


9.7 


.8 


3890 


2.68 


.09 


Iowa 






14 


5.9 


.5 


2293 


1.48 


.06 


Missouri . . 






13 


9.4 


.8 


2035 


2.05 


.10 


South Dakota 






4 


15.5 


1.1 


2950 


3.51 


.12 


Nebraska 






14 


11.1 


.8 


2732 


2.64 


.10 


Kansas 






6 


5.2 


.6 


2658 


1.82 


.07 





















Cost of Growing Potatoes 



311 





CO 

w E H 

m E p 
o 


Average 


State or Territory 


Miles 
to Ship- 
ping 
■ point 


Days 

for 

Round 

Trip 


Pounds 

in One 

Load 


Cost 
per 
Load 


Cost 
per 100 
Pounds 


Kentucky .... 


19 


12.4 


1.4 


1834 


4.44 


.24 


Tennessee .... 


19 


10.0 


.8 


1874 


1.99 


.11 


Alabama 


8 


14.0 


1.2 


1450 


3.14 


.22 


Mississippi .... 


11 


11.9 


1.1 


1336 


2.85 


.21 


Louisiana .... 


6 


12.6 


1.3 


1400 


4.00 


.29 


Texas 


26 


12.4 


1.1 


1460 


2.86 


.20 


Indian Territory . . 


3 


7.9 


.6 


1867 


1.65 


.09 


Arkansas 


11 


13.6 


1.3 


.1523 


3.04 


.20 


Montana 


9 


14.0 


1.2 


2811 


5.47 


.19 


Wyoming .... 


5 


25.5 


2.3 


2860 


9.20 


.32 


Colorado 


20 


12.2 


1.1 


3100 


4.71 


.15 


New Mexico .... 


3 


22.7 


2.1 


1800 


9.09 


.50 


Utah 


5 


10.1 


.7 


3300 


2.31 


.07 


Idaho 


4 


15.5 


1.4 


3125 


5.17 


.17 


Washington .... 


15 


7.8 


.8 


2617 


3.38 


.13 




9 


9.7 


.9 


4028 


3.15 


.08 


California .... 


7 


12.0 


1.1 


4914 


4.72 


.10 


Geographic division : 














North Atlantic . 


94 


7.0 


.7 


2717 


2.55 


.09 


South Atlantic . 


102 


9.6 


.9 


1871 


2.74 


.15 


North Central . . 


193 


8.1 


.7 


2651 


2.30 


.09 


South Central . . 


103 


12.1 


1.2 


1660 


3.30 


.20 


Western .... 


77 


11.3 


1.0 


3615 


4.05 


.11 


States and Territories 














represented . . . 


569 


8.2 


.7 


2679 


2.34 


.09 



312 



The Potato 



Table XXXII. Cost of Hauling Potatoes prom Most 
Remote Farms to Shipping Points, as Reported 



State or Territory 



Miles to 

Shipping 

Point 


Days for 

Round 

Trip 


16.0 


1.0 


13.0 


1.0 


15.0 


1.0 


19.0 


1.0 


10.0 


.5 


15.0 


1.0 


25.0 


3.0 


15.0 


1.5 


16.0 


1.0 


15.0 


1.0 


12.0 


1.0 


46.0 


5.0 


40.0 


4.0 


50.0 


4.0 


15.0 


1.5 


30.0 


2.5 


24.0 


2.0 


30.0 


2.0 


15.0 


2.0 


24.0 


1.5 


30.0 


2.0 


30.0 


2.0 


30.0 


2.0 


13.0 


1.0 


20.0 


2.0 


30.0 


3.0 


37.5 


3.0 


9.5 


1.0 


37.5 


5.0 


35.0 


3.0 


37.5 


4.0 


30.0 


2.5 


25.0 


3.0 


46.0 


4.0 


15.0 


.5 



Pounds 

in One 

Load 



Cost per 
Load 



Cost per 

100 
Pounds 



Maine . . . 
New Hampshire 
Vermont . . 
Massachusetts 
Rhode Island . 
Connecticut . 
New York . . 
New Jersey 
Pennsylvania . 
Delaware . 
Maryland . 
Virginia . . 
West Virginia 
North Carolina 
South Carolina 
Georgia . . . 
Florida . . . 
Ohio . . . 
Indiana 
Illinois . . . 
Michigan . . 
Wisconsin . 
Minnesota . . 
Iowa . . . 
Missouri . . 
South Dakota 
Nebraska . . 
Kansas . . 
Kentucky . . 
Tennessee . . 
Alabama . . 
Mississippi 
Louisiana . 
Texas . . 
Indian Territory 



1600 
2000 
3000 
3500 
1500 
2000 
3000 
3500 
3500 
1500 
4000 
3000 
3500 
1600 
1600 
2000 
1500 
2000 
3250 
3500 
3500 
2500 
3000 
2000 
1500 
3000 
4000 
3000 
1800 
1500 
1200 
1500 
900 
3000 
2000 



$3.50 
4.00 
3.50 
4.75 
1.50 
4.00 

12.00 
5.62 
4.00 
4.00 
5.00 

20.00 
8.00 

11.00 
3.75 
5.00 
5.00 
8.00 
6.00 
6.00 
6.00 
6.00 
7.00 
3.00 
3.00 
7.50 
9.00 
2.50 

15.00 
8.25 

10.00 
6.88 

12.00 
7.52 

13.75 



Cost of Groioing Potatoes 



313 



State oe Territory 



Arkansas . 
Montana . 
Wyoming . 
Colorado . 
New Mexico 
Utah . . . 
Idaho . , . 
Washington 
Oregon . . 
California . 



Miles to 

Shipping 

Point 


Days for 

Round 

Trip 


Pounds 

in One 

Load 


Cost per 
Load 


40.0 


2.5 


2250 


7.50 


30.0 


3.0 


3500 


13.50 


55.0 


6.5 


4500 


22.75 


70.0 


7.0 


2500 


33.00 


57.5 


4.0 


2000 


22.00 


25.5 


2.5 


3000 


8.75 


25.0 


3.0 


2500 


10.50 


30.0 


3.0 


800 


12.00 


35.0 


3.0 


2000 


13.50 


32.0 


3.0 


4000 


12.75 



Cost per 

100 

Pounds 



.33 

.39 

.51 

1.40 

1.10 

.29 

.42 

1.50 

.68 

.32 



INDEX 



Africa, production of potatoes in, 3. 

alcohol, manufacture of, 274. 
slops or residue, 282. 
use for, 271. 

alfalfa in rotation, 111, 112. 

alsike clover in rotation, 111. 

Aroostook County, Me., as a potato 
center, 7, 113. 

arsenical injury, 202. 

Asia, production of potatoes in, 3. 

association of characters in breed- 
ing, 75. 

Australia, production of potatoes 
in, 3. 

Austria-Hungary, production of 
potatoes in, 2, 3. 

bacteria in soils, 102. 

bacterial wilt, 200. 

Baker, 21. 

barley, value in United States, 3. 

world's crop, 1. 
Bauhin, 15. 
belladonna, 1. 
black-leg, 199. 
blister-beetle, 175. 
bordeaux mixture, 217. 
botanical characteristics, 21. 
breeding, 47-85 (chapter IV). 
bud-selection, 57. 
bud-sports, 57, 76. 

calcium, 124. 

Canada, production of potatoes in, 
3, 13. 

de Candolle, 15. 

capsicum, 1. 

Carbondale, Colo., as a potato cen- 
ter, 7. 

Cardan, 15. 



Chester County, Pa., potatoes con- 
sumed on farms, 12. 
Cierca de Leon, 14. 
classification, 21. 
climate, 86 (chapter V). 
Clusius, 15. 

Colorado potato beetle, 170. 
composition of potatoes, 262. 
constitutional degeneracy, 205. 
control measures against disease, 

206-225 (chapter XI). 
corn, value in United States, 3. 

world's crop, 1. 
cost of growing potatoes, 287-313 
(chapter XV). 

harvesting, 234. 

hauling, 307. 
cotton, value in United States, 3. 
cover-crops, 105. 
critical period, 89, 95. 
crop reporter, 257. 
crossing, method of, 78. 
cultivation of potato, 163. 
culture of potato, 89. 
curly dwarf, 203 ; control, 206. 
cutting seed, 156. 
cyanimid as fertilizer, 120, 121. 

Dala potato, 73. 
Darwin, 76. 

description of potato, 22. 
desiccated potatoes, 284. 
digging, methods of, 230, 
disease, 97. 

from organisms in soil, 212. 

proof varieties, 50, 221. 
diseases of potato, 183-205 (chapter 

X). 
Dodge, 70. 
drainage, 95. 



315 



316 



Index 



Early and late potatoes, marketing, 

249. 
early blight, 189. 
East, 74, 78, 82, 83. 
eastern shore of Va. and Md. as 

potato centers, 7. 
egg-plant, 1. 
engines, 165. 

England, introduction into, 15. 
Europe, production of' potatoes in, 

3. 
European Russia, production of 

potatoes in, 2. 
expense of marketing, 255. 

family consumption, statistics, 11. 
farm manures, 130. 
fertilizer practices, 115, 126. 
fertilizers, 113 (chapter VI). 

market forms, 116. 
Fischer, 75, 76. 
Fitch, 25, 27, 30, 33. 
flea-beetles, 173. 
flour, potato, 284. 
France, production of potatoes in, 

2, 3. 
freight charges, 253. 
Fruwirth, 73, 74. 
Funk, 11. 
fusarium dry rot, 196. 

wilt, 195. 

Gerard, 16. 

Germany, production of potatoes 

in, 2, 3. 
yields to the acre, 12. 
grading, 245. 
Great Britain, yields to the acre, 

12. 
Greeley, Colo., as a potato center, 7. 
green manures, 105. 
growing crop, care of, 160 (chapter 

VIII). 

hand planting, 151. 
harvest, time to, 226. 
harvesting cost, 234. 

labor, 234. 

potatoes, 226-235 (chapter XII). 



hauling, cost of, 307. 
hay-plants, 109. 

value of in United States, 3. 
heat, 90. 
heated cars, 253. 
henbane, 1. 
Herbal, 16. 
Heriot, 47. 

hill and drill planting, 146. 
hill selection, 54. 

history of potato, 14 (chapter II). 
human food, uses as, 260. 
Humboldt, 15. 

hybridization, improvement by, 
77-84. 

ideals of the potato crop, 48, 49. 
improvement, methods of, 56. 
individual selection, 62. 
insects, 170-182 (chapter IX). 
Ireland, introduction into, 16. 
Irish famine, 20. 

Kaw Valley, as a potato center, 7. 
Kohler, 31, 33. 

late blight, 190; treatment, 214. 
leaf-hoppers, 129. 
leaf roll, 204 ; control, 206. 
Livingston County, N. Y., potatoes 

consumed on farms, 11. 
local dealers, marketing through, 

243. 

McCormick variety, resistant to 
heat, 91. 

Macoun, 12. 

Maine, production of potatoes in, 
3. 

manures and fertilizers, 113 (chap- 
ter VI). 

marketing through local dealers, 
243. 

markets, 249. 

and marketing, 237-258 (chap- 
ter XIII). 

mass-selection, 61. 

Michigan, production of potatoes 
in, 3. 



Index 



317 



Mil ward, 33. 

Minnesota, production of potatoes 

in, 3. 
mosaic, control, 206. 
Myers, 59. 

net necrosis, 203. 
Newman, 73. 

New York, production of potatoes 
in, 3. 
State Potato Ass'n, score card 
of, 53. 
nitrate of lime, 120. 
nitrogen, 119. 

Norfolk, Va., as a potato center, 7. 
North America, introduction into, 
15. 
production of potatoes in, 3. 

oats, value in United States, 3. 

world's crop, 1. 
Orton, 73. 

packages, 245. 

papas, 16. 

Paradisus, 16. 

Parkinson, 16. 

Parmentier, 18. 

pedigree breeding, 62. 

Penn., production of potatoes in, 3. 

Peru, original home of potato, 14. 

Phipps, 20. 

phosphorus, 122. 

picking and sorting, 232. 

plant food, 94, 114. 

planting, 133-142 (chapter VII). 

hill and drill, 146. 

tools, 148. 
potassium, 123. 
potato flour, 284. 

plant louse, 177. 

pomace, 283. 

stalk weevil, 179. 

wart, 198. 
"Potatoes of Virginia," 18. 

value in United States, 3. 
poultry food, 283. 
powdery scab, 201. 
power for potato fields, 165. 



price of potato land, 88. 

prices, 250. 

production on farms, statistics, 7. 

world, 2. 

in different countries, 2. 
pure lines, 58. 

quality when cooked, 261. 

Raleigh, Sir Walter, 15. 

red clover in rotation, 111. 

Red River Valley, as a potato 

center, 7. 
rhizoctoniose, 194. 
rice, world's crop, 1. 
Rose, 14. 

rotation, 86 (chapter V). 
running out of varieties, 72. 
Russia, production of potatoes in, 
3. 

Sacramento, Cal., as a potato 

center, 7. 
Salaman, 78, 82, 83, 84. 
San Joaquin, Cal., as a potato 

center, 7. 
scab, common, 199. 

powdery, 201. 
score-card, 152. 
seed, cutting, 156. 

potatoes, 152. 

treatment for scab, 153, 208. 

selection, 55, 57. 
shipping, 246. 
silver scurf, 196. 
soils, 86 (chapter V) . 
soil texture, 93. 
Solanum Cardiophyllum, 21. 

Commersonii, 21. 

Jamesii, 21. 

Maglia, 21. 

oxycarpum, 21. 

tuberosum, 21. 
sorting, 232. 
South America, production of 

potatoes in, 3. 
Spain, introduction into, 15. 
Spillman, 12, 70. 
spindling sprout, 203. 



318 



Index 



stalk borer, 180. 

starch manufacture, 265. 

use for, 265, 270. 
stock food, use as, 280. 
storage, 258. 
Stuart, 27, 33, 43, 45. 
sulphur, 126. 
survey results, growing costs, 296. 

texture of cooked potatoes, 263. 
three-lined leaf-beetle, 176. 
tillage, results of, 137. 

tools, 135. 
tip-burn, 168, 202. 
tobacco, 1. 

value in United States, 3. 
tomato, 1. 
tools, tillage, 35. 
tortoise beetles, 176. 
tractors, 165. 

tuber-unit, method of breeding, 62. 
types of potato growing, 97. 

United Kingdom, production of 

potatoes in, 2. 
United States, production of 

potatoes in, 2, 3. 
yields to the acre, 12. 



Uses of potato, 259-286 (chapter 
XIV). 

varieties of Iowa and central west, 

25. 
verticillium wilt, 196. 

Waid's experiments, 72. 
Warren, 11. 

water requirements, 92. 
Webber, 62. 
weed killing, 140. 

wheat value in United States, 
3. 
world's crop, 1. 
white grubs, 180. 
wild potatoes, 47. 
Wilson, 81. 
wire worms, 181. 

Wisconsin, production of potatoes 
in, 3. 

yield, highest recorded in United 

States, 12. 
yields, 12, 87. 

Zavitz, 71. 



Printed in the United States of America. 



HPHE following pages contain advertisements of a 
few of the Macmillan books on kindred subjects 



Cost of Growing Potatoes 305 

land was plowed twice in the spring with frequent culti- 
vation, which very nearly destroys every trace of quack- 
grass. The low cost of hand labor on the field warrants 
the statement that weed growth was practically de- 
stroyed by cultivation before the potatoes were planted, 
and by the weeder after they were planted. It is impor- 
tant that we impress upon the users of weeders and smooth- 
ing harrows the absolute necessity of beginning opera- 
tion at once after the potatoes or seeds have been planted. 
If the weeds become rooted, even though they may not 
show very much above ground, the light-fingered tools, 
which are only safe to use on the growing plants, will 
have very little effect upon them. Farmers are often 
disappointed in the effect of weeders, simply because the 
weeder has given the weed the same encouragement which 
it gives to the plant under cultivation. 

"The seed potatoes which were kept in an outdoor pit 
during the winter were taken from the pit April 18th, 
spread thinly on the barn floor and stirred occasionally to 
prevent long sprouts from growing. They were planted 
at varying dates from May 28th to June 10th. None 
of the sprouts were broken in handling or planting. The 
pieces were cut as nearly cubical as possible, and weighed 
about 2 oz. each. The number of eyes varied from 1 to 
5, the seed ends often containing 5 to 6 eyes. No effort 
was made to reduce the size of the seed piece from the 
seed end of the potato, in fact it is a fatal error to do so. 
Only one or two stalks will develop. The pieces were 
dropped 14| inches by 36 inches." 

"The cost by items does not show marked difference 
for the two years, with the exception of digging and 
delivering. A part of this saving was due to a lighter 
yield and a part to more economical methods of handling." 



306 The Potato 

Four and One-third Acres Potatoes (1910) 



Yield, 958| bushels (large) at 40 cents 
Yield, 53 bushels (small) at 20 cents . 

Plowing 

Harrowing 

Planting 

Cultivating 

Hoeing, hand labor 

Spraying, 1050 gallons per acre . . . 

Digging and delivering 

73| bushels seed at 40 cents . . . 

8234 pounds fertilizer 

42 pounds paris green 

Profit, $75.87 



$15.33 
9.75 
18.63 
13.02 
3.81 
40.70 
63.32 
29.40 

111.57 
12.60 



$318.13 



$383.40 
10.60 



$394.00 



Potatoes 



Cost per Acbe 

Yield (large), 289f bushels at 40 cents 
Yield (small), 27 bushels at 20 cents . 
Yield (large), 221| bushels at 40 cents 
Yield (small), 12.2 bushels at 20 cents 

Plowing 

Harrowing 

Planting 

Cultivating 

Hoeing (hand labor) 

Spraying, 1000 gallons 

Spraying, 1050 + gallons 

Digging and delivering 

Seed, 16 bushels at 73 cents . . . . 
Seed, 17 bushels at 40 cents . . . . 

Fertilizer, 1800 pounds 

Fertilizer, 1900 + pounds 

Paris green, 7 pounds 

Paris green, 9.6 + pounds 

Total cost per acre 

Profit per acre 



1909 



$115.92 
5.40 



4.18 
1.90 
4.30 
1.73 

.68 
8.49 

24.01 
11.68 

25.20 

2.10 



$84.27 
37.05 



1910 



$88.48 
2.44 



3.54 
2.25 
4.30 
3.00 



9.39 
14.61 

6.80 

25.75 

2.91 



$73.43 
17.49 



Cost of Growing Potatoes 307 

Place — Minnesota. 

Authority — Bulletin 48, Bureau of Statistics, by Hays 
and Parker. 

The cost of producing potatoes, under garden condi- 
tions, is given on pages 308 and 309. 

Cost of hauling 

Potatoes are a bulky crop and the cost of hauling is 
no inconsiderable item. Andrews x says : " In many ways 
they are hauled under conditions similar to those under 
which grain is hauled, and the average cost per 100 pounds 
for hauling potatoes from farms to shipping points is the 
same as for wheat and 2 cents more than for oats, corn 
or barley. 

"The averages for the United States are affected more 
by the figures for the north Atlantic and north central 
states than by the other states and the territories, since 
about three-fourths of the potato crop of the United 
States is produced east of the Rocky Mountains and 
north of the Potomac and Ohio rivers and southern 
boundaries of Missouri and Kansas. 

"The average cost of hauling from farms to shipping 
points in this region is 9 cents per 100 pounds, or 5.4 
cents per bushel. The lowest average cost is for three 
counties in Rhode Island, where an average of three trips 
per day is made to and from shipping points, and the 
highest average cost in the north Atlantic and north 
central states is in South Dakota, where the average 
time of round trip between farm and shipping point is 
longer than one working day." 

1 Andrews. Cost of Hauling Crops from Farms to Shipping Points. 
U. S. D. A., Bureau of Statistics, Bui, 49. 



308 



The Potato 





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Cost of Growing Potatoes 



309 



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310 



The Potato 



Table XXXI. — Average Cost op Hauling Potatoes from 
Farms to Shipping Points 









m 
8 fc fr* 

a s « 

S 5 o 


Average 


State or Territory 


Milea 


Days 


Pounds 


Cost 


Cost 




o 


Ping 
Point 


Round 
Trip 


in One 
Load 


per 
Load 


per 100 
Pounds 


Maine 


9 


7.6 


0.7 


2393 


$2.58 


$0.11 


New Hampshire 




5 


6.6 


.6 


2330 


2.21 


.09 


Vermont . 




7 


7.1 


.6 


2321 


1.93 


.08 


Massachusetts 






3 


10.6 


.6 


2300 


2.40 


.10 


Rhode Island 






3 


5.0 


.3 


1933 


.98 


.05 


Connecticut . 






2 


6.7 


.7 


2500 


2.80 


.11 


New York 






34 


7.1 


.7 


2896 


2.49 


.09 


New Jersey . 






9 


4.8 


.6 


2583 


2.08 


.08 


Pennsylvania 






22 


6.6 


.7 


2809 


2.61 


.09 


Delaware 


1 


10.6 


.7 


1500 


2.80 


.19 


Maryland . . 






7 


5.7 


.5 


2536 


1.62 


.06 


Virginia 






22 


9.1 


.8 


1880 


2.30 


.12 


West Virginia 






17 


12.2 


1.2 


1965 


4.21 


.21 


North Carolina 






27 


11.4 


1.1 


1437 


2.92 


.20 


South Carolina 






3 


9.9 


.7 


1267 


2.01 


.16 








16 


11.0 


1.0 


1466 


2.52 


.17 


Florida . . 






9 


7.7 


.6 


1544 


2.05 
2.39 


.13 


Ohio 


22 


7.2 


.7 


2748 


.09 


Indiana . . 






12 


6.4 


.6 


3075 


1.72 


.06 


Illinois . . 






13 


6.0 


.6 


2700 


1.94 


.07 


Michigan . 






47 


8.0 


.7 


2766 


2.25 


.08 


Wisconsin 






28 


9.5 


.8 


2595 


2.46 


.09 


Minnesota 






20 


9.7 


.8 


3890 


2.68 


.09 


Iowa . . . 






14 


5.9 


.5 


2293 


1.48 


.06 


Missouri . . 






13 


9.4 


.8 


2035 


2.05 


.10 


South Dakota 






4 


15.5 


1.1 


2950 


3.51 


.12 


Nebraska 






14 


11.1 


.8 


2732 


2.64 


.10 


Kansas 






6 


5.2 


.6 


2658 


1.82 


.07 





















Cost of Growing Potatoes 



311 







H g " 
3 E O 

p£ * 




Average 


State ob Territory 


Miles 
to Ship- 
ping 
point 


Days 

for 

Round 

Trip 


Pounds 

in One 

Load 


Cost 
per 
Load 


Cost 
per 100 
Pounds 


Kentucky 
Tennessee 
Alabama . 
Mississippi 
Louisiana 
Texas . 




19 
19 

8 
11 

6 
26 

3 
11 


12.4 
10.0 
14.0 
11.9 
12.6 
12.4 
7.9 
13.6 


1.4 
.8 
1.2 
1.1 
1.3 
1.1 
.6 
1.3 


1834 
1874 
1450 
1336 
1400 
1460 
1867 
1523 


4.44 
1.99 
3.14 
2.85 
4.00 
2.86 
1.65 
3.04 


.24 
.11 
.22 
.21 
.29 
.20 


Indian Territory . . 


.09 
.20 


Wyoming 
Colorado . . 

New Mexico . 
Utah . . . 




9 
5 

20 
3 
5 
4 

15 
9 
7 


14.0 
25.5 
12.2 
22.7 
10.1 
15.5 
7.8 
9.7 
12.0 


1.2 

2.3 
1.1 

2.1 
.7 

1.4 
.8 
.9 

1.1 


2811 
2860 
3100 
1800 
3300 
3125 
2617 
4028 
4914 


5.47 
9.20 
4.71 
9.09 
2.31 
5.17 
3.38 
3.15 
4.72 


.19 
.32 
.15 
.50 
.07 


Idaho . 




.17 


Washington . 
Oregon . . 
California 




.13 
.08 
.10 


Geographic division : 
North Atlantic . . 
South Atlantic . . 
North Central . ■. 
South Central . . 
Western .... 


94 
102 
193 
103 

77 


7.0 

9.6 

8.1 

12.1 

11.3 


.7 

.9 

.7 

1.2 

1.0 


2717 
1871 
2651 
1660 
3615 


2.55 

2.74 
2.30 
3.30 
4.05 


.09 
.15 
.09 
.20 
.11 


States and Ten 
represented 


itories 


569 


8.2 


.7 


2679 


2.34 


.09 



312 



The Potato 



Table XXXII. Cost of Hauling Potatoes from Most 
Remote Farms to Shipping Points, as Reported 



State oh Territory 



Maine . . . 
New Hampshire 
Vermont . . 
Massachusetts 
Rhode Island . 
Connecticut . 
New York . . 
New Jersey 
Pennsylvania . 
Delaware . 
Maryland . 
Virginia . . 
West Virginia 
North Carolina 
South Carolina 
Georgia . . . 
Florida . . . 
Ohio . . . 
Indiana . . 
Illinois . . . 
Michigan . 
Wisconsin . 
Minnesota . 
Iowa 

Missouri . . 
South Dakota 
Nebraska . . 
Kansas . . 
Kentucky . 
Tennessee . . 
Alabama . . 
Mississippi 
Louisiana . 
Texas . . . 
Indian Territory 



Miles to 

Shipping 

Point 


Days for 

Round 

Trip 


Pounds 

in One 

Load 


Cost per 
Load 


16.0 


1.0 


1600 


$3.50 


13.0 


1.0 


2000 


4.00 


15.0 


1.0 


3000 


3.50 


19.0 


1.0 


3500 


4.75 


10.0 


.5 


1500 


1.50 


15.0 


1.0 


2000 


4.00 


25.0 


3.0 


3000 


12.00 


15.0 


1.5 


3500 


5.62 


16.0 


1.0 


3500 


4.00 


15.0 


1.0 


1500 


4.00 


12.0 


1.0 


4000 


5.00 


46.0 


5.0 


3000 


20.00 


40.0 


4.0 


3500 


8.00 


50.0 


4.0 


1600 


11.00 


15.0 


1.5 


1600 


3.75 


30.0 


2.5 


2000 


5.00 


24.0 


2.0 


1500 


5.00 


30.0 


2.0 


2000 


8.00 


15.0 


2.0 


3250 


6.00 


24.0 


1.5 


3500 


6.00 


30.0 


2.0 


3500 


6.00 


30.0 


2.0 


2500 


6.00 


30.0 


2.0 


3000 


7.00 


13.0 


1.0 


2000 


3.00 


20.0 


2.0 


1500 


3.00 


30.0 


3.0 


3000 


7.50 


37.5 


3.0 


4000 


9.00 


9.5 


1.0 


3000 


2.50 


37.5 


5.0 


1800 


15.00 


35.0 


3.0 


1500 


8.25 


37.5 


4.0 


1200 


10.00 


30.0 


2.5 


1500 


6.88 


25.0 


3.0 


900 


12.00 


46.0 


4.0 


3000 


7.52 


15.0 


.5 


2000 


13.75 



Cost per 

100 
Pounds 



Cost of Growing Potatoes 



313 



State ob Territory 



Arkansas . 
Montana . 
Wyoming . 
Colorado . 
New Mexico 
Utah . . . 
Idaho . . 
Washington 
Oregon . . 
California . 



Miles to 

Shipping 

Point 


Days for 

Round 

Trip 


Pounds 

in One 

Load 


Cost per 
Load 


40.0 


2.5 


2250 


7.50 


30.0 


3.0 


3500 


13.50 


55.0 


6.5 


4500 


22.75 


70.0 


7.0 


2500 


33.00 


57.5 


4.0 


2000 


22.00 


25.5 


2.5 


3000 


8.75 


25.0 


3.0 


2500 


10.50 


30.0 


3.0 


800 


12.00 


35.0 


3.0 


2000 


13.50 


32.0 


3.0 


4000 


12.75 



Cost per 

100 
Pounds 



.33 

.39 

.51 

1.40 

1.10 

.29 

.42 

1.50 

.68 

.32 



INDEX 



Africa, production of potatoes in, 3. 
alcohol, manufacture of, 274. 
slops or residue, 282. 
use for, 271. 
alfalfa in rotation, 111, 112. 
alsike clover in rotation, 111. 
Aroostook County, Me., as a potato 

center, 7, 113. 
arsenical injury, 202. 
Asia, production of potatoes in, 3. 
association of characters in breed- 
ing, 75. 
Australia, production of potatoes 

in, 3. 
Austria-Hungary, production of 
potatoes in, 2, 3. 

bacteria in soils, 102. 

bacterial wilt, 200. 

Baker, 21. 

barley, value in United States, 3. 

world's crop, 1. 
Bauhin, 15. 
belladonna, 1. 
black-leg, 199. 
blister-beetle, 175. 
bordeaux mixture, 217. 
botanical characteristics, 21. 
breeding, 47-85 (chapter IV). 
bud-selection, 57. 
bud-sports, 57, 76. 

calcium, 124. 

Canada, production of potatoes in, 
3, 13. 

de Candolle, 15. 

capsicum, 1. 

Carbondale, Colo., as a potato cen- 
ter, 7. 

Cardan, 15. 



Chester County, Pa., potatoes con- 
sumed on farms, 12. 
Cierca de Leon, 14. 
classification, 21. 
climate, 86 (chapter V). 
Clusius, 15. 

Colorado potato beetle, 170. 
composition of potatoes, 262. 
constitutional degeneracy, 205. 
control measures against disease, 

206-225 (chapter XI). 
corn, value in United States, 3. 

world's crop, 1. 
cost of growing potatoes, 287-313 
(chapter XV). 

harvesting, 234. 

hauling, 307. 
cotton, value in United States, 3. 
cover-crops, 105. 
critical period, 89, 95. 
crop reporter, 257. 
crossing, method of, 78. 
cultivation of potato, 163. 
culture of potato, 89. 
curly dwarf, 203 ; control, 206. 
cutting seed, 156. 
cyanimid as fertilizer, 120, 121. 

Dala potato, 73. 
Darwin, 76. 

description of potato, 22. 
desiccated potatoes, 284. 
digging, methods of, 230, 
disease, 97. 

from organisms in soil, 212. 

proof varieties, 50, 221. 
diseases of potato, 183-205 (chapter 

X). 
Dodge, 70. 
drainage, 95. 



315 



316 



Index 



Early and late potatoes, marketing, 

249. 
early blight, 189. 
East, 74, 78, 82, 83. 
eastern shore of Va. and Md. as 

potato centers, 7. 
egg-plant, 1. 
engines, 165. 

England, introduction into, 15. 
Europe, production of potatoes in, 

3. 
European Russia, production of 

potatoes in, 2. 
expense of marketing, 255. 

family consumption, statistics, 11. 
farm manures, 130. 
fertilizer practices, 115, 126. 
fertilizers, 113 (chapter VI). 

market forms, 116. 
Fischer, 75, 76. 
Fitch, 25, 27, 30, 33. 
flea-beetles, 173. 
flour, potato, 284. 
France, production of potatoes in, 

2, 3. 
freight charges, 253. 
Fruwirth, 73, 74. 
Funk, 11. 
fusarium dry rot, 196. 

wilt, 195. 

Gerard, 16. 

Germany, production of potatoes 

in, 2, 3. 
yields to the acre, 12. 
grading, 245. 
Great Britain, yields to the acre, 

12. 
Greeley, Colo., as a potato center, 7. 
green manures, 105. 
growing crop, care of, 160 (chapter 

VIII). 

hand planting, 151. 
harvest, time to, 226. 
harvesting cost, 234. 

labor, 234. 

potatoes, 226-235 (chapter XII). 



hauling, cost of, 307. 
hay-plants, 109. 

value of in United States, 3. 
heat, 90. 
heated cars, 253. 
henbane, 1. 
Herbal, 16. 
Heriot, 47. 

hill and drill planting, 146. 
hill selection, 54. 

history of potato, 14 (chapter II). 
human food, uses as, 260. 
Humboldt, 15. 

hybridization, improvement by, 
77-84. 

ideals of the potato crop, 48, 49. 
improvement, methods of, 56. 
individual selection, 62. 
insects, 170-182 (chapter IX). 
Ireland, introduction into, 16. 
Irish famine, 20. 

Kaw Valley, as a potato center, 7. 
Kohler, 31, 33. 

late blight, 190 ; treatment, 214. 
leaf-hoppers, 129. 
leaf roll, 204 ; control, 206. 
Livingston County, N. Y., potatoes 

consumed on farms, 11. 
local dealers, marketing through, 

243. 

McCormick variety, resistant to 
heat, 91. 

Macoun, 12. 

Maine, production of potatoes in, 
3. 

manures and fertilizers, 113 (chap- 
ter VI). 

marketing through local dealers, 
243. 

markets, 249. 

and marketing, 237-258 (chap- 
ter XIII). 

mass-selection, 61. 

Michigan, production of potatoes 
in, 3. 



Index 



317 



Milward, 33. 

Minnesota, production of potatoes 

in, 3. 
mosaic, control, 206. 
Myers, 59. 

net necrosis, 203. 
Newman, 73. 

New York, production of potatoes 
in, 3. 
State Potato Ass'n, score card 
of, 53. 
nitrate of lime, 120. 
nitrogen, 119. 

Norfolk, Va., as a potato center, 7. 
North America, introduction into, 
15. 
production of potatoes in, 3. 

oats, value in United States, 3. 

world's crop, 1. 
Orton, 73. 

packages, 245. 

papas, 16. 

Paradisus, 16. 

Parkinson, 16. 

Parmentier, 18. 

pedigree breeding, 62. 

Penn., production of potatoes in, 3. 

Peru, original home of potato, 14. 

Phipps, 20. 

phosphorus, 122. 

picking and sorting, 232. 

plant food, 94, 114. 

planting, 133-142 (chapter VII). 

hill and drill, 146. 

tools, 148. 
potassium, 123. 
potato flour, 284. 

plant louse, 177. 

pomace, 283. 

stalk weevil, 179. 

wart, 198. 
"Potatoes of Virginia," 18. 

value in United States, 3. 
poultry food, 283. 
powdery scab, 201. 
power for potato fields, 165. 



price of potato land, 88. 

prices, 250. 

production on farms, statistics, 7. 

world, 2. 

in different countries, 2. 
pure lines, 58. 

quality when cooked, 261. 

Raleigh, Sir Walter, 15. 

red clover in rotation, 111. 

Red River Valley, as a potato 

center, 7. 
rhizoctoniose, 194. 
rice, world's crop, 1. 
Rose, 14. 

rotation, 86 (chapter V). 
running out of varieties, 72. 
Russia, production of potatoes in, 
3. 

Sacramento, Cal., as a potato 

center, 7. 
Salaman, 78, 82, 83, 84. 
San Joaquin, Cal., as a potato 

center, 7. 
scab, common, 199. 

powdery, 201. 
score-card, 152. 
seed, cutting, 156. 

potatoes, 152. 

treatment for scab, 153, 208. 

selection, 55, 57. 
shipping, 246. 
silver scurf, 196. 
soils, 86 (chapter V). 
soil texture, 93. 
Solanum Cardiophyllum, 21. 

Commersonii, 21. 

Jamesii, 21. 

Maglia, 21. 

oxycarpum, 21. 

tuberosum, 21. 
sorting, 232. 
South America, production of 

potatoes in, 3. 
Spain, introduction into, 15. 
Spillman, 12, 70. 
spindling sprout, 203. 



318 



Index 



stalk borer, 180. 

starch manufacture, 265. 

use for, 265, 270. 
stock food, use as, 280. 
storage, 258. 
Stuart, 27, 33, 43, 45. 
sulphur, 126. 
survey results, growing costs, 296. 

texture of cooked potatoes, 263. 
three-lined leaf-beetle, 176. 
tillage, results of, 137. 

tools, 135. 
tip-burn, 168, 202. 
tobacco, 1. 

value in United States, 3. 
tomato, 1. 
tools, tillage, 35. 
tortoise beetles, 176. 
tractors, 165. 

tuber-unit, method of breeding, 62. 
types of potato growing, 97. 

United Kingdom, production of 

potatoes in, 2. 
United States, production of 

potatoes in, 2, 3. 
yields to the acre, 12. 



Uses of potato, 259-286 (chapter 
XIV). 

varieties of Iowa and central west, 

25. 
verticillium wilt, 196. 

Waid's experiments, 72. 

Warren, 11. 

water requirements, 92. 

Webber, 62. 

weed killing, 140. 

wheat value in* United States, 

3. 
world's crop, 1. 
white grubs, 180. 
wild potatoes, 47. 
Wilson, 81. 
wire worms, 181. 
Wisconsin, production of potatoes 

in, 3. 

yield, highest recorded in United 

States, 12. 
yields, 12, 87. 

Zavitz, 71. 



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